TranslatePsy-AfriSLM: High-Quality Data Scaling For Low-Resource Machine Translation

Milan Gritta, Patrik Lambert, Jihye Back, Amril Nazir


Abstract
The rapid progress in Artificial Intelligence has largely bypassed African languages, creating a digital divide that limits AI adoption on the continent. Recent open-source LLMs systematically underperform on African language machine translation, while the lack of large-scale, high-quality, open-source parallel data has constrained the development of competitive small language models (SLMs). We introduce TranslatePsy-AfriSLM, a collection of open-source machine translation resources for 19 Sub-Saharan African languages, including curated parallel data, African-specialized synthetic data, and a family of fine-tuned SLMs. Our empirical study shows that unified quality-estimation filtering removes up to 96% of training tokens without degrading quality, and that filtered synthetic data dominates the quality-efficiency Pareto frontier. Fine-tuned on the resulting data mixture, TranslatePsy-AfriSLMs outperform substantially larger systems, including TranslateGemma-27B and Qwen3.5-122B-A10B, with as few as 0.8B parameters.
Anthology ID:
2026.emnlp-main.1686
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
38348–38375
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1686/
DOI:
Bibkey:
Cite (ACL):
Milan Gritta, Patrik Lambert, Jihye Back, and Amril Nazir. 2026. TranslatePsy-AfriSLM: High-Quality Data Scaling For Low-Resource Machine Translation. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 38348–38375, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
TranslatePsy-AfriSLM: High-Quality Data Scaling For Low-Resource Machine Translation (Gritta et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1686.pdf