> so you won't need a key to read the translated poetry

This probably sounds like a crazy question, but if you are already getting translations using someone else's API keys, can't you just store/cache that response so that the next time the translation is requested, you already have it?

get a few personal gmail accounts's gemini API key, and you have 1000s of free LLM calls to flash-lite models, which are more than upto this task. one time run, and save it to your db.