Well I study Ukrainian and was just curious why it's missing, since it's on the supported list for both whisper and OpenAI TTS. I can't find a list of languages supported by GPT-4o anywhere in the release materials or API documents. It's not in GPT-4 technical report either.

I'm native in Finnish and would say that 4o writes sort of ok Finnish but definitely makes many mistakes. I'd imagine many of the languages on the list of supported ones are worse.