Terminology Rarity Predicts Catastrophic Failure in LLM Translation of Low-Resource Ancient Languages: Evidence from Ancient Greek

A study evaluated large language models (Claude, Gemini, ChatGPT) translating Ancient Greek texts, finding high performance on previously translated works (95.2/100) but declining quality on untranslated technical texts (79.9/100). Terminology rarity was identified as a strong predictor of translation failure, with rare terms causing catastrophic performance drops.