Yep, the entire UI should be navigable via keyboard. I'm not quite sure what you mean by visual indicators, but all image buttons have alt text.
I'm sorry for how long it has taken for me to get back to you.
What I mean by visual indicators is, for instance, the toggled status of a button, the health of a player on their character icon, the unavailability of an option ETC.
Another thing to look out for which I neglected to mention before is exclusively visual puzzles. I.E a puzzle that you couldn't do blindfolded. Asking the player to look at something, move colored tiles, pick a picture out, remember the detail of a painting that wasn't described in text ETC.
Just things to check for. :)