Human Evaluation of the Usefulness of Fine-Tuned English Translators for the Guarani Mbya and Nheengatu Indigenous Languages

We investigate how useful are machine translators based on the fine-tuning of LLMs with very small amounts of training data, typical of extremely low-resource languages such as Indigenous languages. We started by developing translators for the Guarani Mbya and Nheengatu languages by fine-tuning a WMT- 19 German-English translator. We then performed a human evaluation of the usefulness of the results of test sets and compared them to their SacreBLUE scores. We had a level of alignment around 60-70%, although there were about 40% of very wrong translations. The results suggest the need of a filter for bad translations as a way to make the translators useful, possibly only in scenarios of human-AI collaboration such as writing-support assistants.