You do good videos, go for it.
Biab did not have VST Sync back then but it works the same way as now.
EZkeys will work on any track, you don't need a chord track on the EZKeys track as it will only play the chord notes, you have to drag n drop the "Chords" track into EZkeys to give EZKeys a chord progression, then you simply replace the whole track with browser midi or sections of track with different browser midi. Just make sure the keys the same or it will transpose the chords.
That's the way I got it to work, but maybe there is another way ???
In the pic I have EZKeys playing a Midi Super Track.

It should be the same deal with EZBass, isn't it the same thing as I'm doing here in videos ?
https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=758019

https://www.dropbox.com/s/b8fouoy73alr2fd/BB23-EZBass-PlayableRealTracks.mp4?dl=0