I like the idea of a touch interface. I implemented it for the 3D maze here: Two-player 3D game demo: The Dungeon of Lamurloq (first-person POV dungeon crawler)
The picture of the maze is touchable: middle for forward, left / right to turn left/right.
Note that, on small mobile phones, you may have to choose “Desktop mode” to get the correct layout (*)
It’s also possible to adjust the labels as you suggest. I tried with multi-replace but it was becoming a chore… and my kid kept asking random questions about Choicescript, I had to cut it short. 
(*) Yes, the images could be all scaled down with heavy *script-ing, if one really wanted.