Here is a very simple way, these are 2 simple Reaper scripts that will import selected Biab mixer tracks directly into Reaper instantly.
Insert new track import bb temp txt data.zip
Import bb temp txt data section to selected track.zip
To insert new section of track into Reaper, delete the section you don't like then in Biab on an empty track use Alt+F8 to generate up the RT section you need then run the script to transfer to selected track in Reaper.
This allows you to change any section you like as you don't have a consolidated wav file, it uses your source wma or wav files.
**DON'T use the "move" option when saving in Reaper, it will load the files direct from the RealTracks and RealDrums folders same as Biab will do.
If you open a frozen SGU in Biab it will import the tracks without having to generate them up first.

Zoom++

https://stash.reaper.fm/u/ReaTrak (Scripts for Biab Reaper)
Open SGU in Reaper Instantly