Register-based data selection for multilingual LLMs

Tomasz Galica, Amanda Myntti, Erik Henriksson, Fedor Vitiugin, Sampo Pyysalo, Veronika Laippala


Abstract
The development of high-quality multilingual models depends on well-curated multilingual datasets, which are typically obtained through filtering large web-crawled corpora. Such filtering approaches must be effective across a wide range of languages in order to improve model quality proportionally across the entire linguistic space. In recent years multiple Natural Language Processing (NLP) approaches for data processing and Large Language Model (LLM) training were developed. However, the most significant progress has been made for rich-resource languages such as English and Chinese, leaving multilingual methods largely underexplored. In this work, we present data selection strategies based on Internet registers (genres) and Web Document Score (WDS). We study 15 European languages utilizing HPLT 3.0 datasets. We train and evaluate four small generative language models per language, and compare how specific registers and WDS affect model training in separate and combined approaches. We use five common evaluation tasks covering models’ linguistic, knowledge-based, and reasoning skills. We analyze the impact of the studied strategies on each language, their average performance, and show how combining register-based selection with WDS improves evaluation performance. These results indicate that both registers and WDS can generalize across multiple languages, offering a new path towards multilingual data filtering.
Anthology ID:
2026.findings-emnlp.4
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
52–67
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.4/
DOI:
Bibkey:
Cite (ACL):
Tomasz Galica, Amanda Myntti, Erik Henriksson, Fedor Vitiugin, Sampo Pyysalo, and Veronika Laippala. 2026. Register-based data selection for multilingual LLMs. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 52–67, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Register-based data selection for multilingual LLMs (Galica et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.4.pdf