Meaning Over Morphology: A Multi-Metric Benchmark of LLMs for Bangla Dialect Translation

Soumik Deb Niloy, Subhey Sadi Rahman, Mahbub E Sobhani, Md. Golam Rabiul Alam, Farig Yousuf Sadeque, Md. Rezuwan Hassan


Abstract
Regional dialects of Bangla, such as Sylheti and Chittagonian, pose significant challenges for natural language processing due to their low-resource nature and substantial linguistic variation from standard Bangla. In this work, we present a systematic evaluation of eight open-source LLMs for translating fifteen distinct Bangla dialects into standard Bangla. To achieve this comprehensive coverage, we utilize a combination of established benchmarks and a novel dataset curated from an ongoing regional linguistic project. We assess model performance using a multi-metric framework that combines exact-match and error-rate evaluations such as, Averaged BLEU, WER, and CER with embedding-based semantic metrics including BERTScore, METEOR, and COMET. Additionally, we perform a detailed dialect-level linguistic analysis to identify the deep-seated structural, orthographic, and semantic barriers inherent to dialectal translation. Our study highlights the strengths and limitations of current open-source models, provides empirical insights for future dialect-aware fine-tuning, and contributes a reproducible benchmark for the research community.
Anthology ID:
2026.dialres-1.24
Volume:
Proceedings of the First Workshop on Dialects in NLP — A Resource Perspective
Month:
May
Year:
2026
Address:
Palma de Mallorca
Editors:
Antonis Anastasopoulos, Stella Markantonatou, Angela Ralli, Marcos Zampieri, Stavros Bompolas, Vivian Stamou
Venues:
DialRes | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
238–255
Language:
External URL:
https://lrec.elra.info/lrec2026-ws-dialres-24
DOI:
10.63317/3h8y7fs2zbq4
Bibkey:
Cite (ACL):
Soumik Deb Niloy, Subhey Sadi Rahman, Mahbub E Sobhani, Md. Golam Rabiul Alam, Farig Yousuf Sadeque, and Md. Rezuwan Hassan. 2026. Meaning Over Morphology: A Multi-Metric Benchmark of LLMs for Bangla Dialect Translation. In Proceedings of the First Workshop on Dialects in NLP — A Resource Perspective, pages 238–255, Palma de Mallorca. Association for Computational Linguistics.
Cite (Informal):
Meaning Over Morphology: A Multi-Metric Benchmark of LLMs for Bangla Dialect Translation (Niloy et al., DialRes 2026)
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