Benchmarking Large Language Models for Detecting Satirical Code-Mixed Sentences
Organizations: National University of Science and Technology POLITEHNICA Bucharest, Bucharest, Romania · Academy of Romanian Scientists, Bucharest, Romania · Center for Data Science in Humanities, Chosun University, South Korea · National Institute for Research & Development in Informatics - ICI Bucharest, Bucharest, Romania ·
Abstract
Code-switching is a natural linguistic phenomenon, yet its impact on high-level reasoning tasks remains largely unexplored in under-resourced languages like Romanian. Natural language processing tasks, such as satire detection, rely heavily on nuanced cultural and syntactic cues that large language models struggle to capture. In this paper, we investigate four methods (i.e., random replacement, phrase translation, dependency parsing, and large language models) for generating synthetic code-mixed Romanian sentences with English, German, French, and Italian. We start with an existing dataset for satire detection, compiled from Romanian news articles and annotated at the sentence level by humans, and augment it with over 600k samples, namely CS-SeLeRoSa. We provide an in-depth analysis of the dataset generation process. Then, we evaluate several multilingual large language models across zero-shot, chain-of-thought, and fine-tuning regimes on both the synthetic corpus and a human-adjudicated gold benchmark, namely CS-SeLeRoSa-Gold. While older open models suffer substantial degradation (dropping to 37%-55% macro-F1), newer models like Gemma 4 31B achieve 68.1% zero-shot, rivaling frontier models like GPT-5 mini (69.5%). Furthermore, fine-tuning significantly reduces formatting errors and improves the results, increasing Gemma 4 31B to 77.5% on CS-SeLeRoSa and 72.6% on the gold standard, outperforming frontier zero-shot baselines.
Figures & tables
| Language | ||||
|---|---|---|---|---|
| RO | EN | DE | FR | IT |
| 13,873 | 165,725 | 165,725 | 165,725 | 165,803 |
| Model | SeLeRoSa | CS-SeLeRoSa | CS-SeLeRoSa-Gold | ||||||
|---|---|---|---|---|---|---|---|---|---|
| ZS | CoT | FT | ZS | CoT | FT | ZS | CoT | FT | |
| Llama 3.1 8B | 46.3 ±11.1 | 53.3 ±1.9 | 69.0 ±0.1 | 44.8 ±15.2 | 47.9 ±2.2 | 74.9 ±0.8 | 43.0 ±12.8 | 43.2 ±2.2 | 65.7 ±0.0 |
| Gemma 3 27B | 49.9 ±0.6 | 53.2 ±0.4 | 74.3 ±1.3 | 37.0 ±0.3 | 41.3 ±1.8 | 75.4 ±0.8 | 36.1 ±0.8 | 39.1 ±3.2 | 67.2 ±0.8 |
| Gemma 4 26B A4B | 67.0 ±0.0 | 68.1 ±0.5 | 70.2 ±0.5 | 63.7 ±0.1 | 64.3 ±0.1 | 70.2 ±0.6 | 58.2 ±0.3 | 61.5 ±0.3 | 63.7 ±0.8 |
| Gemma 4 31B | 70.2 ±0.1 | 69.4 ±0.1 | 78.3 ±0.8 | 68.1 ±0.0 | 66.5 ±0.0 | 77.5 ±0.1 | 61.8 ±0.2 | 63.0 ±0.5 | 72.6 ±0.4 |
| RoMistral 7B | 41.2 ±11.5 | 49.6 ±0.6 | 72.5 ±1.4 | 36.8 ±14.4 | 48.3 ±1.0 | 74.6 ±0.6 | 35.7 ±13.7 | 46.6 ±1.5 | 70.4 ±0.5 |
Appendix figures & tables33 assets
Supplementary material from the paper’s appendix.
Appendix
| Model | BLEU | chrF | TER | COMET |
|---|---|---|---|---|
| RO EN | ||||
| Gemma 3 12B | 41.04 | 67.30 | 46.23 | 0.89 |
| Gemma 3 27B | 42.80 | 69.37 | 43.31 | 0.90 |
| GPT-5 mini | 40.07 | 67.60 | 46.13 | 0.89 |
| RO DE | ||||
| Gemma 3 12B | 23.61 | 52.45 | 70.19 | 0.82 |
| Method | CMI | M-Index | I-Index | LE | SP-Avg |
|---|---|---|---|---|---|
| RO EN | |||||
| Random | 39.29 | 0.44 | 0.47 | 0.94 | 0.46 |
| Phrase | 15.93 | 0.18 | 0.22 | 0.55 | 0.21 |
| Dependency | 18.75 | 0.21 | 0.16 | 0.57 | 0.16 |
| LLM | 18.64 | 0.21 | 0.19 | 0.62 | 0.21 |
| RO DE | |||||
| Method | BERTScore | Jaccard | ||||
|---|---|---|---|---|---|---|
| Mean | Std | Median | Mean | Std | Median | |
| RO EN | ||||||
| Random | 8.03 | 1.91 | 7.90 | 73.28 | 7.85 | 72.77 |
| Phrase | 3.33 | 1.51 | 3.37 | 29.80 | 13.23 | 30.68 |
| Dependency | 3.31 | 0.95 | 3.22 | 37.37 | 6.53 | 37.89 |
| LLM | 3.61 | 2.05 | 3.08 | 39.06 | 19.66 | 34.41 |
| Label | Method | Original (RO) | Code-Switched | Translated (EN) |
| RO EN | ||||
| Satire | Phrase | Ăla poate să distrugă şi şalele transplantate, şi pe ale tale. | Ăla poate să destroy şi şalele transplantate, şi pe ale tale. | That one can destroy both the transplanted loins and your own. |
| LLM | De s , i sunt pe cartelă, după ce consumam net, primeam altul. | De s , i sunt pe cartelă, after I consumam net, primeam another one. | Although I am on a prepaid card, after I consumed the internet, I would receive another one. | |
| Regular | Random | Totul din lemn, calitate norvegiană. | Everything din wood, quality Norwegian. | Everything made of wood, Norwegian quality. |
| Dependency | Cât să mai răbdăm, că nici noi nu suntem de fier! | Cât să mai răbdăm, that we are not made of iron either! | How much more must we endure, since we are not made of iron either! | |
| RO DE | ||||
| Model Name | Checkpoint | Size |
| Gemma 3 12B | google/gemma-3-12b-it | 12B |
| Gemma 3 27B | google/gemma-3-27b-it | 27B |
| Gemma 4 26B A4B | google/gemma-4-26B-A4B-it | 26B |
| Gemma 4 31B | google/gemma-4-31B-it | 31B |
| Llama 3.1 8B | meta-llama/Llama-3.1-8B-Instruct | 8B |
| RoGemma 2 9B | OpenLLM-Ro/RoGemma2-9b-Instruct-DPO | 9B |
| Language | Adjudicated | Keep | AR (%) |
|---|---|---|---|
| English | 199 | 117 | 58.8% |
| German | 159 | 70 | 44.0% |
| French | 198 | 118 | 59.6% |
| Italian | 159 | 86 | 54.1% |
| Total | 715 | 391 | 54.7% |
| Lang. | CP | LA | MP | CQ | Acc. |
|---|---|---|---|---|---|
| English | -0.001 | 1.373 | 2.070 | 1.844 | 94.0 |
| German | 0.770 | 1.883 | 1.004 | 1.333 | 90.6 |
| French | 0.209 | 1.232 | 2.127 | 1.833 | 93.4 |
| Italian | 0.156 | 1.759 | 1.468 | 1.884 | 91.8 |
| All | 0.556 | 1.858 | 2.089 | 1.858 | 92.9 |
| Criterion | Agreement (%) | |
|---|---|---|
| Class Preservation | 0.178 | 85.0% |
| Linguistic Acceptability | 0.603 | 72.3% |
| Meaning Preservation | 0.609 | 76.5% |
| CS Quality | 0.655 | 66.6% |
| Final Verdict | 0.518 | 75.9% |
| Language | CP | LA | MP | CSQ | Verdict |
|---|---|---|---|---|---|
| English | 0.205 | 0.476 | 0.629 | 0.679 | 0.438 |
| German | 0.315 | 0.723 | 0.503 | 0.731 | 0.634 |
| French | -0.024 | 0.364 | 0.644 | 0.514 | 0.416 |
| Italian | 0.220 | 0.672 | 0.675 | 0.670 | 0.617 |
| Method | EN | DE | FR | IT | Total |
|---|---|---|---|---|---|
| Random | 4 | 1 | 9 | 3 | 17 |
| Phrase | 25 | 12 | 26 | 17 | 80 |
| Dependency | 43 | 26 | 39 | 31 | 139 |
| LLM | 45 | 31 | 44 | 35 | 155 |
| Total | 117 | 70 | 118 | 86 | 391 |
| Statistic | Value |
|---|---|
| Total samples | 391 |
| Unique source sentences | 50 |
| CS methods | 4 |
| Target languages | 4 |
| K values | 3 |
| Satire samples | 218 (55.8%) |
| Method | CMI | M-Index | I-Index | LE | SP-Avg |
|---|---|---|---|---|---|
| RO EN | |||||
| Random | 24.60 | 0.28 | 0.34 | 0.65 | 0.34 |
| Phrase | 15.51 | 0.18 | 0.21 | 0.56 | 0.21 |
| Dependency | 23.47 | 0.26 | 0.19 | 0.68 | 0.19 |
| LLM | 17.14 | 0.20 | 0.20 | 0.59 | 0.20 |
| RO DE | |||||
| Model | Zero-Shot | Chain-of-Thought | Fine-Tuning | |||
|---|---|---|---|---|---|---|
| Acc (%) | F1 (%) | Acc (%) | F1 (%) | Acc (%) | F1 (%) | |
| Llama 3.1 8B | 43.9 ±14.9 | 46.3 ±11.1 | 52.2 ±2.3 | 53.3 ±1.9 | 69.0 ±0.1 | 69.0 ±0.1 |
| Gemma 3 27B | 53.0 ±0.4 | 49.9 ±0.6 | 55.5 ±0.2 | 53.2 ±0.4 | 74.9 ±1.4 | 74.3 ±1.3 |
| Gemma 4 26B A4B | 66.9 ±0.0 | 67.0 ±0.0 | 68.0 ±0.5 | 68.1 ±0.5 | 70.1 ±0.5 | 70.2 ±0.5 |
| Gemma 4 31B | 70.2 ±0.1 | 70.2 ±0.1 | 69.4 ±0.1 | 69.4 ±0.1 | 78.5 ±0.8 | 78.3 ±0.8 |
| RoMistral 7B | 39.7 ±14.2 | 41.2 ±11.5 | 48.6 ±0.2 | 49.6 ±0.6 | 73.1 ±1.7 | 72.5 ±1.4 |
| Model | Zero-Shot | Chain-of-Thought | Fine-Tuning | |||
|---|---|---|---|---|---|---|
| Acc (%) | F1 (%) | Acc (%) | F1 (%) | Acc (%) | F1 (%) | |
| Llama 3.1 8B | 46.0 ±24.2 | 47.5 ±21.3 | 48.7 ±2.3 | 49.8 ±2.2 | 60.7 ±3.1 | 60.6 ±3.1 |
| Gemma 3 27B | 42.7 ±2.3 | 39.5 ±2.8 | 46.7 ±7.0 | 44.3 ±8.1 | 68.0 ±5.3 | 66.7 ±5.3 |
| Gemma 4 26B A4B | 52.0 ±0.0 | 51.9 ±0.0 | 60.0 ±0.0 | 60.0 ±0.8 | 57.3 ±2.3 | 56.9 ±2.6 |
| Gemma 4 31B | 64.7 ±1.2 | 63.1 ±1.0 | 66.0 ±2.0 | 64.7 ±2.1 | 72.0 ±2.0 | 70.8 ±1.8 |
| RoMistral 7B | 35.3 ±16.8 | 35.8 ±15.7 | 40.7 ±1.2 | 41.8 ±1.9 | 65.3 ±3.1 | 64.5 ±3.5 |
| Model | Zero-Shot | Chain-of-Thought | Fine-Tuning | |||
|---|---|---|---|---|---|---|
| Acc (%) | F1 (%) | Acc (%) | F1 (%) | Acc (%) | F1 (%) | |
| Llama 3.1 8B | 42.0 ±19.6 | 44.8 ±15.2 | 47.8 ±2.6 † | 47.9 ±2.2 † | 75.8 ±0.2 † | 74.9 ±0.8 † |
| Gemma 3 27B | 44.9 ±0.2 † | 37.0 ±0.3 † | 47.3 ±1.0 † | 41.3 ±1.8 † | 75.7 ±0.9 † | 75.4 ±0.8 † |
| Gemma 4 26B A4B | 63.8 ±0.0 † | 63.7 ±0.1 † | 64.3 ±0.1 † | 64.3 ±0.1 † | 70.2 ±0.6 † | 70.2 ±0.6 † |
| Gemma 4 31B | 68.1 ±0.0 | 68.1 ±0.0 | 66.5 ±0.0 | 66.5 ±0.0 | 78.0 ±0.1 | 77.5 ±0.1 |
| RoMistral 7B | 35.7 ±15.2 | 36.8 ±14.4 | 46.3 ±0.7 † | 48.3 ±1.0 † | 75.8 ±0.2 † | 74.6 ±0.6 † |
| Model | Zero-Shot | Chain-of-Thought | Fine-Tuning | |||
|---|---|---|---|---|---|---|
| Acc (%) | F1 (%) | Acc (%) | F1 (%) | Acc (%) | F1 (%) | |
| Llama 3.1 8B | 40.2 ±17.2 | 43.0 ±12.8 | 43.0 ±2.3 † | 43.2 ±2.2 † | 67.7 ±1.0 † | 65.7 ±0.0 † |
| Gemma 3 27B | 41.9 ±0.7 † | 36.1 ±0.8 † | 43.3 ±2.4 † | 39.1 ±3.2 † | 68.7 ±1.2 † | 67.2 ±0.8 † |
| Gemma 4 26B A4B | 58.2 ±0.3 † | 58.2 ±0.3 † | 61.5 ±0.4 † | 61.5 ±0.3 † | 63.9 ±0.8 † | 63.7 ±0.8 † |
| Gemma 4 31B | 62.4 ±0.3 | 61.8 ±0.2 | 63.6 ±0.4 | 63.0 ±0.5 | 73.9 ±0.3 | 72.6 ±0.4 |
| RoMistral 7B | 35.0 ±14.0 | 35.7 ±13.7 | 44.2 ±1.8 † | 46.6 ±1.5 † | 73.0 ±0.6 | 70.4 ±0.5 † |
| Model | Random | Phrase | Dependency | LLM | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ZS | CoT | FT | ZS | CoT | FT | ZS | CoT | FT | ZS | CoT | FT | |
| RO EN | ||||||||||||
| Llama 3.1 8B | 44.3 ±16.5 † | 44.0 ±4.0 † | 75.6 ±1.1 | 45.4 ±15.9 | 49.8 ±2.1 † | 75.0 ±0.8 | 47.5 ±13.2 | 52.3 ±2.0 | 77.0 ±0.2 | 45.1 ±15.0 | 49.6 ±2.9 † | 74.5 ±0.8 |
| Gemma 3 27B | 30.3 ±0.1 † | 31.0 ±0.9 † | 74.0 ±0.4 | 38.6 ±0.2 † | 41.3 ±1.5 † | 74.4 ±0.8 | 40.8 ±0.6 † | 44.8 ±2.5 † | 75.9 ±1.0 | 33.4 ±0.4 † | 40.0 ±3.9 † | 75.3 ±1.2 |
| Gemma 4 26B A4B | 58.4 ±0.2 † | 54.1 ±0.3 † | 67.7 ±1.4 † | 63.8 ±0.1 † | 63.5 ±0.1 † | 69.5 ±0.7 | 66.9 ±0.1 | 67.0 ±0.2 † | 71.1 ±0.5 | 66.7 ±0.3 | 67.4 ±0.2 | 69.1 ±0.2 |
| Gemma 4 31B | 64.3 ±0.2 † | 58.3 ±0.2 † | 76.4 ±0.4 † | 67.8 ±0.0 † | 66.2 ±0.3 † | 77.0 ±0.2 † | 69.5 ±0.1 | 68.4 ±0.2 † | 78.5 ±0.1 | 69.9 ±0.2 | 68.9 ±0.1 | 77.7 ±0.3 |
| Model | Random | Phrase | Dependency | LLM | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ZS | CoT | FT | ZS | CoT | FT | ZS | CoT | FT | ZS | CoT | FT | |
| RO EN | ||||||||||||
| Llama 3.1 8B | 50.0 ±16.7 | 31.7 ±16.1 | 73.3 ±0.0 | 50.3 ±13.1 | 48.7 ±7.5 | 68.6 ±1.8 | 44.6 ±18.4 | 46.9 ±2.6 | 63.6 ±2.2 | 50.7 ±11.1 | 46.7 ±5.3 | 61.7 ±3.6 |
| Gemma 3 27B | 28.9 ±7.7 | 33.3 ±0.0 | 73.3 ±0.0 | 33.2 ±0.0 | 38.3 ±1.7 | 62.8 ±3.5 | 33.6 ±1.7 | 35.0 ±4.1 | 69.2 ±3.9 | 33.6 ±0.0 | 38.4 ±6.8 | 61.6 ±2.9 |
| Gemma 4 26B A4B | 57.8 ±13.5 | 50.0 ±0.0 | 65.6 ±13.5 | 64.0 ±0.0 | 61.3 ±6.1 | 70.3 ±2.1 | 54.7 ±2.9 | 54.2 ±2.7 | 58.8 ±3.5 | 65.2 ±1.3 | 65.1 ±2.5 | 63.7 ±1.3 |
| Gemma 4 31B | 50.0 ±0.0 | 50.0 ±0.0 | 73.3 ±0.0 | 70.3 ±0.0 | 67.9 ±2.1 | 72.5 ±2.2 | 59.7 ±1.2 | 60.4 ±1.2 | 72.3 ±2.1 | 64.7 ±1.2 | 66.1 ±2.1 | 72.5 ±3.5 |
| Model | Method | F1 (%) | (%) |
|---|---|---|---|
| Llama 3.1 8B | None | 46.3 | - |
| Random | 43.3 | -3.0 | |
| Phrase | 44.7 | -1.6 | |
| Dependency | 46.4 | +0.0 | |
| LLM | 43.9 | -2.4 | |
| Gemma 3 27B | None | 49.9 | - |
| Model | Method | FPR (%) | FNR (%) |
|---|---|---|---|
| Llama 3.1 8B | None | 47.2 | 47.3 |
| Random | 57.4 | 34.1 | |
| Phrase | 52.4 | 39.3 | |
| Dependency | 49.7 | 40.3 | |
| LLM | 52.5 | 40.2 | |
| Gemma 3 27B | None | 76.3 | 4.2 |
| Model | Language | FPR (%) | FNR (%) |
|---|---|---|---|
| Llama 3.1 8B | EN | 51.6 | 37.9 |
| DE | 56.0 | 38.9 | |
| FR | 51.3 | 42.0 | |
| IT | 53.2 | 35.3 | |
| RO | 47.2 | 47.3 | |
| Gemma 3 27B | EN | 93.2 | 1.2 |
| Model | Setting | FPR (%) | FNR (%) |
|---|---|---|---|
| Llama 3.1 8B | Zero-Shot | 63.8 | 49.6 |
| CoT | 74.9 | 19.1 | |
| Fine-Tuning | 20.1 | 30.2 | |
| Gemma 3 27B | Zero-Shot | 92.0 | 1.2 |
| CoT | 87.0 | 2.6 | |
| Fine-Tuning | 26.1 | 21.5 |
| Metric | Seed 1 | Seed 2 | Seed 3 |
|---|---|---|---|
| Zero-Shot | |||
| Predicted Positive | 1,343 | 1,325 | 1,170 |
| Predicted Negative | 721 | 737 | 780 |
| Unparseable | 8 | 10 | 122 |
| Chain-of-Thought | |||
| Predicted Positive | 1,665 | 1,549 | 1,613 |
| ID | Count | Topic Label | Share (%) | Top c-TF-IDF Keywords |
| Reasoning Traces | ||||
| 0 | 319 | Interpreting Satire and Irony | 96.1 | cuvânt, afirma t , ie, exprima, sentiment, satiric, spune |
| 1 | 13 | Romanian Satire Explanations | 3.9 | românesc, român, satiric, cuvânt, sarcasm, comentariu |
| Input Sentences | ||||
| 131 | People Leaving and Changing Positions (Outliers) | 39.5 | pleca, rămâne, veni, începe, urmare, întâmpla | |
| 0 | 71 | Reported Problems and Conditions | 21.4 | totuşi, pericol, fapt, explica, spune, convinşi |
| Model | ZS (%) | CoT (%) | FT (%) |
|---|---|---|---|
| Llama 3.1 8B | 24.00 | 7.91 | 0.13 |
| Gemma 3 27B | 0.00 | 0.00 | 0.02 |
| Gemma 4 26B A4B | 0.12 | 0.29 | 0.15 |
| Gemma 4 31B | 0.07 | 0.04 | 0.00 |
| RoMistral 7B | 24.52 | 10.97 | 0.00 |
| RoLlama 3.1 8B | 2.02 | 0.88 | 0.02 |
| Model | ZS (%) | CoT (%) | FT (%) |
|---|---|---|---|
| Llama 3.1 8B | 23.10 | 6.56 | 0.00 |
| Gemma 3 27B | 0.00 | 0.00 | 0.00 |
| Gemma 4 26B A4B | 0.00 | 0.43 | 0.34 |
| Gemma 4 31B | 0.00 | 0.00 | 0.00 |
| RoMistral 7B | 24.72 | 11.25 | 0.00 |
| RoLlama 3.1 8B | 2.81 | 1.36 | 0.09 |
Code-Switching
Code-switching studies how people combine languages in speech and text and how AI systems can recognize, understand, and generate these mixtures.
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