Efficient Low-Resource Language Adaptation via Multi-Source Dynamic Logit Fusion

Chen Zhang, Jiuheng Lin, Zhiyuan Liao, Yansong Feng


Abstract
Adapting large language models (LLMs) to low-resource languages (LRLs) is constrained by the scarcity of task data and computational resources. Although Proxy Tuning offers a logit-level strategy for introducing scaling effects, it often fails in LRL settings because the large model’s weak LRL competence might overwhelm the knowledge of specialized smaller models. We thus propose TriMix, a test-time logit fusion framework that dynamically balances capabilities from three different sources: LRL competence from a continually pretrained small model, task competence from high-resource language instruction tuning, and the scaling benefits of large models. It is data- and compute-efficient, requiring no LRL task annotations, and only continual pretraining on a small model. Experiments across four model families and eight LRLs show that TriMix consistently outperforms single-model baselines and Proxy Tuning. Our analysis reveals that prioritizing the small LRL-specialized model’s logits is crucial for success, challenging the prevalent large-model-dominant assumption.
Anthology ID:
2026.acl-long.207
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
4540–4557
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.207/
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Bibkey:
Cite (ACL):
Chen Zhang, Jiuheng Lin, Zhiyuan Liao, and Yansong Feng. 2026. Efficient Low-Resource Language Adaptation via Multi-Source Dynamic Logit Fusion. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 4540–4557, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Efficient Low-Resource Language Adaptation via Multi-Source Dynamic Logit Fusion (Zhang et al., ACL 2026)
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https://preview.aclanthology.org/ingest-acl/2026.acl-long.207.pdf
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