We use openwhisper for transcription which accepts a list of "words to look out for" which we populate with a short list of the names of all the people and companies most likely to be mentioned in the text, and then we do a spell checking pass at the end using Gemini with a much longer list, telling it to look out for anything that might be a misspelling.

It's not perfect, but it's taken it from being an issue that made all our transcripts look terrible, to an issue I no longer think about.

I imagine just using the second spellchecking pass with Gemini would be almost as effective.