Just an update: I am still working on this. I kind of decided that I'd do alt text for every illustration in the book... and theres a lot of them. We're doing a big PDF update next month (I think) and I'm hoping this will be part of it.
Viewing post in The Magical Land of Yeld 2nd Edition comments
The alt text seems to be good, but it's unreliable for my screen reader to say it aloud, is it possible to have a second plane .txt doc come with the book containing the text? just a direct copy and paste. navigation is partly working. I can fiddle around on my end see if using a browser instead of acrobat gets better results or anything.