If they had an option to File > Import Frozen SGU
the Plugin could read the chords and track names into the Plugin then get BBW4 to open the same SGU file,
so then BBW4 will write the frozen tracks as wav files or track section data files in SavedTracks, or the Plugin can read the SGU's frozen tracks section to track section data files, not having to run BBW4, this is how it will work if it gets the code in it and plays the files direct.

But all this they should try hard to get away from, just bite the bullet and get the code into the Plugin.
You don't want how it works now dragging out for another 10 years waiting for things to be programed in BBW4 first each time, trying to get away with doing it on the cheap.
In Australia when someone says "she'll be right mate" you just know it's gonna &^%#$ up !

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