I wish "proper nouns only" closed captioning was a thing. "King Byanlethroun of House Herethrofod" can be tough to catch accurately.
My wife speaks English as a second language (very fluently), but sometimes she has trouble with various accents so we leave the closed captions on most of the time. I seem to catch at least two or three transcription errors every time I watch something. I believe AI is used for most transcription, and it does a poor job when it lacks context for the content.