Keybindings are a hard problem. Doubly so when you're a wrapper that has to also not collide with everyone else's keybindings. :)

The idea was that users should spend most of their time in "normal" mode, deferring to "locked" mode only for cases like you mentioned (ctrl-r in bash or in vim). The modal ergonomics are built on that.

I'd ideally like to find one word that describes locked mode better than "locked", which I agree is not ideal. I spent quite some time thinking about it and asking others, but most of us are not native English speakers - so maybe there's something obvious we're missing. :)