Re: Have I got this right?
The text version already exists, so there is no need to transcribe the audio and, if the user wants to see the text, they just need to buy the book at the discounted rate (with my Amazon/Audible account, I can usually get the book/audiobook pair at a big discount).
Subtitles? But that is for film for the hard of hearing. If you are hard of hearing, you are unlikely to have bought the audiobook in the first place.
I agree with you about the foreign language part, but, again, I generally look it up in the written version of the book, if I really can't understand it after repeatedly listening to the sentence - or ask a friend.