If you make a responsive keyboard, which would give a different tactile sensation for CAPS and for lowercase, then it would be easier. Piano gives this kind of distinction, historically it was due to a mechanism behind "FortePiano", in a modern electrical piano it reproduced for a convenience.
It can be made in a mechanical way, like a tristate button -- off, slighly-on, on.
But I'm not too sure how useful it is for efficiency even after practicing so much with it; there are a lot of false positives and negatives since keypress velocity doesn't matter for regular typing. With enough data, you could figure out a specific velocity threshold for each key so that you make fewer mistakes, and then maybe it'd be more helpful.