I agree that it would be good if Dorico were to audition notes when you commit them to the score using the rhythmic duration commands; we’ll add this.
I’m not sure I know what Alt+Enter does for you; is that a custom key command you’ve set up? What does it normally do?
As for making it possible to change shortcuts conditionally based on whether pitch before duration input is active, that’s not possible at the moment, I’m afraid, and unlikely to be so in the near future. But we’ll certainly continue to consider it; we thought about many such situations while we were working on the new input method, but decided against those kinds of changes on the grounds that we didn’t want to make the program too casey and conditional to make it hard to keep track of what key combinations do what in each circumstance.