I have been using GPT-4 to generate i18n files, and it is great. You can see this post to check GPT-4's translation capabilities: https://www.reddit.com/r/visualnovels/comments/11rty62/gpt4_...

I can simply feed in an en.i18n.json file, and it will generate i18n.json files for as many languages as I want. I don't use a specific prompt, but I occasionally include general information about the software in it.

Edit: I do verify the output by translating it back to English using Google translate, but it seems I need to be more careful.