OK I'll say it, rewrite the entire program and do it all. Now that that is out of my system I would rank your suggestions in this order:

"Besides obvious things like proper wording and sorting of some menus - which is more of text correction and re-organizing rather than something new, there had been a few big items proposed that in my view should be considered first." I would put this on the top of the list followed by
#1 - Panels - Which goes along with the above
#5 - Chord View
#3 - Preference menu
#4 - Track View
#2 - Mixer

Just my opinions and YMMV

A good summary Misha.

Doc-take it easy John this is just a sharp scalpel. It will not cut deep so don't worry.
Me-I'm not John
Doc-I know, I am!

64 bit Win 10 Pro, the latest BiaB/RB, Roland Octa-Capture audio interface, a ton of software/hardware