I got a feeling they are flat out doing new things. I don't mind doing without and letting them spend all the time in the world they like for a complete new application.

Yes build4 Midi Super Tracks work, then not after 4.
The only thing that seems to have been changed that might affect this is:

  • Improved: Much faster initialization of accompaniment functions (e.g. StylePicker and RealTracks Picker).

as this is RealBand\Data\bbw2.exe

So I tried it using bbw2.exe from build4 with RealBand.exe build7
and it all seems to work.

To try it out install realband_2017_update_build4.exe
make a copy of RealBand\Data\bbw2.exe (bbw2_4.exe)
install realband_2017_update_build7.exe
rename bbw2.exe to bbw2_7.exe
rename bbw2_4.exe to bbw2.exe.

any problems just run build4 or build7 update again.