a similar approach to solving this:

I usually start a project by loading the original recording to extract chords and tempo map it. Then I import the MIDI file (which doesn't always come in at the right location or tempo)

Once you've tempo mapped the original song, and seen where the 1st bar starts, save the project and close it. Then open just the MIDI file.

Set the tempo in the MIDI file to the same value in the tempo mapped project, and if necessary, move the MIDI to the same starting bar as in the original project. Save as > .MID, then close the MIDI file

Reopen the original tempo mapped project, and import the MIDI file. It should come in at the right place and at the right tempo.

NOTE: I always move the NOW line to zero before importing anything. Some DAWS default to importing MIDI at wherever the NOW line happens to be, regardless of where the MID was in its original file. I don't know if RB does this or not, but it's probably a good idea to reset the song to the beginning before importing.