Sharing as a not physically disabled person who tries to think about and improve accessibility in education.
I think the option to add alt text would be amazing and maybe one of the easier improvements to implement. Although it likely wouldn’t be used by the majority of users, I think there’s only benefits to adding it.
As to visual contrast, text colors, etc. besides iNaturalist implementing their own changes, which would be cool, there are some nice browser plugins that can help (though possibly not with the map text). My partner uses the OpenDyslexic extension, which I think can improve contrast due to the weighted letters.
Given that it takes a lot of time and effort for devs to implement changes, I think it would be cool to pool a list of browser extensions people find useful for improving accessibility on iNat. Maybe if there’s enough, it could be posted eventually as a tutorial or something?
I’ll also note that from what I’ve seen, untranslated parts of pages tend to be a bug and could probably be reported as such. e.g. a bug I posted recently turned out to also be un-translated before it was fixed.