I whipped something up for a friend a few months ago, it's not just fixing timestamps like you've asked, it's processing the whole audio but it does a good job (uses parakeet) and is quite quick.

Download links and a bit of write up here - https://news.ycombinator.com/item?id=48528779#48535207

Honestly you can probably build your own quite easily. I put together a plex player for firetv that does on device subtitling for whatever you're watching. I got sick of having to find subtitles.