Thanks for the suggestions!
You're right that Y should do something (('ve made it a synonym for yy in my eventual post-jam version), and x should be some sort of attack (attack all adjacent enemies, maybe?). G actually already does something (it scrolls the event log to the bottom), although event log scrolling with gj/gk/G is not documented yet.
B and r/R are casualties of my simplifying assumptions (no forward/backward and no free text input), since I'm not sure how either of those things should work in a 2D roguelike game setting, from a gameplay perspective. But I have some ideas about how I might make "backwards" a meaningful concept in the future.