After spending an entire day doing testing, I finally come up with some response to Charlie Fogle, Andrew Peckover, and Musocity.

Charlie Fogle's Method is Not Working
First generate a RealDrum track, convert that track to a RealTrack, before generate again, edit the waveform of that track, and freeze it.
No, it doesn't work. It will only work in the first few minutes, then after you continue working for several minutes, or if you save and close the sgu and reopen it, that "semi-drum-track" becomes empty, and all waveform inside is gone, there is no sound from that track anymore.

Andrew Peckover's Method is Working Great
Copy a RealDrum track to a Utility track, so it becomes an orange audio track, then you can do whatever on that track without restrictions.
The only problem is, each Utility track creats a .wav file in the sgu folder, such as sgu #1.wav, sgu #2.wav, etc, take a lot of spaces.

Musocity's Method
The new VST DAW Pluging 6.0 allows Reaper to play source material directly, but on YouTube it never says Reaper can regen the source material natively.
If using third party scripts, could cause code conflict and other issues, such as MultiPicker loading extremely slow.

Rumors
Unlike RealTrack, RealDrum is neither editable nor regenable.
There are rumors saying starting in BiaB build 1108, a new feature is added, and RealDrum now can be edited and regened like RealTrack.
Is this true?

Audio Edit Window Text
I hope Musocity can come up with some ideas to modify the source code to bold and change size of the fonts.
I have a triple monitors setup, so one monitor is displaying BiaB, another one is displaying movable AEW, it's still very painful to look at the top of AEW trying to figure out which texts are bar number and which texts are Nashville chords.
Really hope the font, color, or size can be changed.

A Canadian music producer, singer songwriter, composer, and professional guitarist.