Set Items in .di data file to MIXFLAG 1
Set Items in .di data file to FADEIN FADEOUT, stretch markers and stretch marker fade to 0
Keep .di files but name ".RTrackTemplate" for drag import from folder or BB VST
you should be able to drag Bass - 1011 Bass, Electric, BritInvasion Ev 120.RTrackTemplate from a SavedTracks folder into a BB VST track
and if the midi is an "RC" Bass - 1011 Bass, Electric, BritInvasion Ev 120_RC.mid it should be able to be dragged into the same track.
Maybe it could automatically import the RC by same name also.
This will work good also in other DAWs when the BB VST is made to play direct allowing saved tracks to be imported/swapped.

Also:
PLAYRATE 1 1 0 -1 0 0 > PLAYRATE 1 1 0 589824 0 0
If the users have another default stretch set other than Elastique Pro

If BBW4 writes the files wav instructions data files to the SavedTracks folder then we have to wait for the programming to be done it BBW4 as all the fixes pertain to that.
The way I see it BBW4 creates those files along with .mid in the SavedTracks folder then the PLUGIN deletes the .di files after reading them in, these can be left there and be created with a new extension from .di to .RTrackTemplate to enable them to be dropped into Reaper directly or the PLUGIN track for other DAWs.

Great suggestions musocity! I'll look into adding them

Another add here:
Older versions of Reaper need Name ""

Is this waiting for the mac version to be finished first before these fixes can be implemented ??
If things were all in one crossplatform these would be fixed by now and released on both versions at the same time, ... and maybe even a Linux version: Band in a Box for linux