They should be integrated, because RebuildUV seems to be a Rhino 1.0 command that hasn’t been updated since then, while Rebuild at least has a dialog and some nice diagnostic information before you hit OK.
Since Rebuild changes both directions I was forced to use RebuildUV just now and just blindly trust that the deviation wasn’t too large, but then I noticed that it also flipped my surface:
Rebuild also forces a change in the U direction, despite unchanged values.
Note how the color changes from orange to red, indicating that the reverse side of the surface now points outward after the RebuildUV operation (and the deviation is unknown at this point).
What are the chances that this can be done for Rhino 9 while at the same time updating the underlying algorithm with the elmo one?