RFMT at WMT 2026 General Translation Task

Ryosuke Matsuda, Keito Kudo, Ryo Fujii, Takumi Ito, Makoto Morishita, Jun Suzuki


Abstract
We participated in the constrained (open-weight) track of the WMT 2026 General MT Task for the English-to-Japanese and Simplified Chinese-to-Japanese directions. Our system builds on Marco-MT-Algharb, a strong open-weight translation model from the previous WMT General MT task. We further fine-tuned this model to generate more natural Japanese translations. To this end, we constructed a Context-Aware JApanese Linguistic Acceptability dataset (CAJALA). During annotation, human annotators were shown multiple paraphrased variants of a segment within its document-level context and asked to select the most natural one. We then back-translated the CAJALA dataset to create parallel data for Direct Preference Optimization (DPO). We also trained the model to perform fill-in-the-middle (FIM) translation, in which the model reconstructs target-side segments from their surrounding document. At inference, we use Minimum Bayes Risk (MBR) decoding, followed by selective FIM post-editing of low-quality segments.
Anthology ID:
2026.wmt-main.73
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:
1344–1371
Language:
URL:
https://aclanthology.org/2026.wmt-main.73/
DOI:
Bibkey:
Cite (ACL):
Ryosuke Matsuda, Keito Kudo, Ryo Fujii, Takumi Ito, Makoto Morishita, and Jun Suzuki. 2026. RFMT at WMT 2026 General Translation Task. In Proceedings of the Eleventh Conference on Machine Translation, pages 1344–1371, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
RFMT at WMT 2026 General Translation Task (Matsuda et al., WMT 2026)
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PDF:
https://aclanthology.org/2026.wmt-main.73.pdf