Many good ideas.
This is an interesting ramification with the Copy Articulations feature. As I said in a thread last year:
This is because fingerings are a property of notes, and tied values are a single note. I imagine the team might feel this is not necessary. For a finger substitution such as “2-1” I don’t recall ever seeing the rhythmic position specified.
This works for me, at least in Dorico 4.3 and earlier.
After some thought I understand what you mean about accidentals – I suspect that may be too difficult to implement because of casting-off recursion – but I don’t know what you mean about rests.