I would like to see a gif where you attempt the same thing you've done in Reaper but this time do it in BIAB on a single Utility Track. Demonstrate highlighting a bar and regenerate just those highlighted bars in BIAB and also regenerate the region 5 times like you've done in Reaper and come to the forum and place a ✔or X if you accomplished the task in BIAB or not.
✔ - Means BIAB can do it.
X - Means you were unable to do the task.

PG Music says that using a Utility Track you can:

1. Generate RealTracks on a Utility Track.

2. You can generate the ENTIRE RealTrack from the track menu, complete with RealCharts.

3. You can also generate highlighted sections of the Utility track.

4. You can change the highlighted section to a completely different RealTracks instrument.

5. Cross fades will automatically create smooth transitions.

6. You can non-destructively convert a mono track into a stereo track so a stereo instrument can be merged with a mono instrument.

7. Regions regenerated multiple times can be seen and auditioned and selected using Undo/Redo command.

BIAB Ultra Pak+ 2024:RB 2024, Latest builds: Dell Optiplex 7040 Desktop; Windows-10-64 bit, Intel Core i7-6700 3.4GHz CPU and 16 GB Ram Memory.