there are some tools.
don't have the links handy, but there's one made by theo and another made by npckc.
both are on itch.
Viewing post in Deluge: Threnody of Crashing Waves comments
Thank you, I think this is it: Caption Tool for Ren'Py by npckc (itch.io)
I'm going to look into how big of a project it would be to implement this (without completely refactoring the game.)
From what I've found I have a feeling it may be a bit of a project, but maybe I'm being pessimistic. If anyone from the blind community (or otherwise) is interested in helping with this please feel free to contact me.