Hy-MT2-1.8B for WMT26: Staged Multilingual Adaptation for Chinese–Southeast Asian Translation

Ma Ziwei


Abstract
We present a Hy-MT2-1.8B system for the WMT26 Chinese–Southeast Asian translation task, covering fourteen translation directions between Chinese and seven Southeast Asian languages. The system uses a staged adaptation pipeline consisting of monolingual continued pretraining followed by bilingual supervised fine-tuning. We compare parameter-efficient LoRA SFT with full-parameter SFT from the same continued-pretraining checkpoint under matched data and evaluation conditions. On 26,474 validation examples, full-parameter SFT achieves higher macro-average sacreBLEU and COMET scores than LoRA SFT, although the gains vary across language directions. The implementation separates data construction, model preparation, quality evaluation, and serving so that the submitted system can be reproduced and evaluated under the shared-task conditions.
Anthology ID:
2026.wmt-main.184
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:
2397–2404
Language:
URL:
https://aclanthology.org/2026.wmt-main.184/
DOI:
Bibkey:
Cite (ACL):
Ma Ziwei. 2026. Hy-MT2-1.8B for WMT26: Staged Multilingual Adaptation for Chinese–Southeast Asian Translation. In Proceedings of the Eleventh Conference on Machine Translation, pages 2397–2404, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Hy-MT2-1.8B for WMT26: Staged Multilingual Adaptation for Chinese–Southeast Asian Translation (Ziwei, WMT 2026)
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PDF:
https://aclanthology.org/2026.wmt-main.184.pdf