Cross-linguistic Readability and Controllable Difficulty: A Corpus-Based Comparison of Human and LLM Translations of Children’s Literature in Romanian

Karla Csuros, Madalina Chitez, Roxana Rogobete


Abstract
Translation can systematically alter text difficulty, particularly when moving into morphologically rich languages. This study examines whether readability-constrained Large Language Models (LLMs) can mitigate difficulty shifts observed in English–Romanian translation of children’s literature. We construct a paired four-condition corpus comprising English originals, published Romanian translations, readability-constrained LLM translations, and human readability adaptations (12 aligned passages; approx. 23,000 words). Readability is assessed using a Romanian grade-level index (LEMI) designed to be educationally comparable to Flesch–Kincaid Grade Level (FKGL), the cross-linguistic LIX metric, and morphologically informed measures derived from spaCy. Published Romanian translations are significantly more difficult than their English originals, showing higher LIX scores, grade-level estimates, and increased morphological variation. Readability-constrained LLM translation substantially reduces difficulty relative to the published versions (median delta approx. −1.46 grade levels), with significant decreases in LIX, morphological feature density, and lexical diversity (MTLD). Human adaptation yields a smaller reduction (median delta approx. −0.26). Although the direct comparison between LLM and human adaptation is marginal (p = .055, r = 0.64), LLM outputs generally produce larger reductions. These findings demonstrate that translation-induced difficulty shifts are measurable and that controllable LLM translation can modulate readability across structural, lexical, and morphological dimensions in multilingual educational contexts.
Anthology ID:
2026.determit-1.1
Volume:
Proceedings of the 2nd Workshop on Evaluating Text Difficulty in a Multilingual Context (DeTermIt! 2026)
Month:
May
Year:
2026
Address:
Palma, Mallorca (Spain)
Editors:
Giorgio Maria Di Nunzio, Federica Vezzani, Liana Ermakova, Hosein Azarbonyad, Jaap Kamps
Venues:
DeTermIt | WS
SIG:
Publisher:
ELRA Language Resources Association (ELRA)
Note:
Pages:
1–11
Language:
External URL:
https://lrec.elra.info/lrec2026-ws-determit-01
DOI:
10.63317/4yotwqa9fti4
Bibkey:
Cite (ACL):
Karla Csuros, Madalina Chitez, and Roxana Rogobete. 2026. Cross-linguistic Readability and Controllable Difficulty: A Corpus-Based Comparison of Human and LLM Translations of Children’s Literature in Romanian. In Proceedings of the 2nd Workshop on Evaluating Text Difficulty in a Multilingual Context (DeTermIt! 2026), pages 1–11, Palma, Mallorca (Spain). ELRA Language Resources Association (ELRA).
Cite (Informal):
Cross-linguistic Readability and Controllable Difficulty: A Corpus-Based Comparison of Human and LLM Translations of Children’s Literature in Romanian (Csuros et al., DeTermIt 2026)
Copy Citation: