Since you’re using the laudable approach of “do it right or don’t do it at all”, I think with a program that relies heavily on:
users with extensive experience on other software and deeply engrained workflows and/or
a wide variety of available input media (mouse/MIDI/various controllers/…),
I think it would be great to accommodate the widest possible key command/mouse button customization, ideally paired with a GUI along the lines of those nice help screens!
You could even think about offering key command/mouse customization right in the various option and properties screens, so that if I see a (for me) important property, I can assign a key command right there and immediately.
IIRC Dorico already has ways to reassign shortcuts, but ultimately trying to mimic other programs just prolongs the curve of learning to use Dorico. The big problem as I see it is that the shortcuts available in Dorico are not all available in one place (yet) so we are constantly learning about new shortcuts and pop-up conventions that already exist. I hope documentation catches up by the time of the first program upgrade.
I think the current key commands editor is a pretty reasonable start, and I think we would probably in the short- to medium-term be better served by devoting our limited development time towards more core functionality, but in the long-term, sure, we can certainly try to improve the key commands editor.
For many of us, it’s necessary to reassign shortcuts because we don’t have the US keyboard layout. Some shortcuts are either impractical or just plain unavailable to us with international layouts. A graphical editor would be nice, but I have no problem whatsoever with the present solution.