This is very cool! I think softlocks are a slightly inevitable consequence of this sort of design, but it's interesting to look at how other games with meta-puzzles — A Monster's Expedition, for example — cater for it. I think allowing players to reset a room (and designing the puzzles to account for that) ends up being a player-friendly way of dealing with the problem. It can increase the potential for shenanigans, but better to deal with those than to subject players to massive undo-chains!
(speaking of which: I'd consider allowing a more rapid, gently accelerating undo if the player holds Z. There were a few occasions where I had to backtrack a lot and the single tap Z was a bit annoying)
Anyway, those are little gripes and the main thing is that the individual puzzles, and broader puzzle, were very fun to figure out :)