issues 1, 3, 6, 7, 8 and the last 10 are resolved or a solution has been found.
ISSUE 2 : almost completely solved
I'm just coming back to you to let you know a little thing about issue 2.
On windows, at the bottom of the midi window, when you put 1.5 for example for the first resizing digit, the midi transport bar stretches strangely whereas it doesn't on mac. It's not very embarrassing but it's not very beautiful.
WINDOWS 10
without resizing
with resizing 1.5
MAC OS 10.15.7
without resizing
with resizing 1.5