Cross-lingual Evaluation of Multilingual Text Generation

Shamil Chollampatt, Minh-Quang Pham, Sathish Reddy Indurthi, Marco Turchi

Abstract: Scaling automatic evaluation of multilingual text generation of LLMs to new tasks, domains, and languages remains a challenge. Traditional evaluation on benchmark datasets carries the risk of reference data leakage in LLM training or involves additional human annotation effort. The alternative strategy of using another LLM as a scorer also faces uncertainty about the ability of this LLM itself to score non-English text. To address these issues, we propose an annotation-free cross-lingual evaluation protocol for multilingual text generation. Given an LLM candidate to be evaluated and a set of non-English inputs for a particular text generation task, our method first generates English references from the translation of the non-English inputs into English. This is done by an LLM that excels in the equivalent English text generation task. The non-English text generated by the LLM candidate is compared against the generated English references using a cross-lingual evaluation metric to assess the ability of the candidate LLM on multilingual text generation. Our protocol shows a high correlation to the reference-based ROUGE metric in four languages on news text summarization. We also evaluate a diverse set of LLMs in over 90 languages with different prompting strategies to study their multilingual generative abilities.