MTG-LIRA: Scaling Neural Machine Translation for Low-Resource Indian Languages through Multilingual Learning and Synthetic Data

Vedarth Hede, Neha Gupta, Harish Bapat, Harsh Ekbote


Abstract
MTG-LIRA’s submission for the WMT 2026 Low-Resource Indic Language Translation Shared Task presents a unified, scalable multilingual Transformer architecture developed using OpenNMT-py to address severe data scarcity across several low-resource Indian languages. The framework partitions languages into family-based groupings—such as Indo-Aryan and Tibeto-Burman—to optimize cross-lingual knowledge sharing and vocabulary overlap using Byte Pair Encoding (BPE). Data preparation integrates official WMT datasets, the BPCC multilingual corpus, and ~5 million synthetic English–Mizo sentence pairs generated via Meta’s NLLB model, all cleaned using a rigorous preprocessing pipeline. Experimental results across task directions demonstrate that combining multilingual base models with targeted, language-specific adaptation strategies yields significant gains: fine-tuning on domain-specific data improved BLEU scores for English→Assamese (12.17 to 14.44) and English→Mizo (16.2 to 22.72); checkpoint averaging of the 5 best models enhanced stability for English↔Manipuri (Meitei Mayek); a weighted 3:1 checkpoint averaging strategy improved performance for English→Bodo; and zero-shot style direct transfer proved effective for Assamese→English and English→Manipuri (Bengali script) due to shared script features.
Anthology ID:
2026.wmt-main.153
Volume:
Proceedings of the Eleventh Conference on Machine Translation
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Barry Haddow, Tom Kocmi, Philipp Koehn, Christof Monz
Venues:
WMT | WS
SIG:
SIGMT
Publisher:
Association for Computational Linguistics
Note:
Pages:
2146–2153
Language:
URL:
https://aclanthology.org/2026.wmt-main.153/
DOI:
Bibkey:
Cite (ACL):
Vedarth Hede, Neha Gupta, Harish Bapat, and Harsh Ekbote. 2026. MTG-LIRA: Scaling Neural Machine Translation for Low-Resource Indian Languages through Multilingual Learning and Synthetic Data. In Proceedings of the Eleventh Conference on Machine Translation, pages 2146–2153, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
MTG-LIRA: Scaling Neural Machine Translation for Low-Resource Indian Languages through Multilingual Learning and Synthetic Data (Hede et al., WMT 2026)
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https://aclanthology.org/2026.wmt-main.153.pdf