You reached out to the devs and only got generic responses? That's discouraging... :( ah well. Hoping you manage to implement it, and maybe they'll reconsider if you send a pull request with the work already done.
Very nice to know you design your UIs with accessibility in mind from the start! Though my vision is so low that I have to rely on a screen reader software to read the text aloud for me, so an amplified mockup image wouldn't do. I would need something like a navigable HTML page. I guess I'll just wait until you reach the implementing stage.