So have you generated all the tracks up in RB then want to change the some chords ?
Or what to change the chords and regenerate all the tracks again ?
The above method will just change the chords easier than going through and changing each one.
In RB I just saved it as SGU
opened SGU in BB, find replace, saved
RB File - Import - SGU
This is what I got and it took 5 mins:

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