If you look at the different pop/rock/jazz UserTrack templates you will see the type of chords being played. There would be chord substitutions/transposing going on for unavailable chords.
I made some solo instruments that played in different keys and scales in the UserTrack forum, they were in a Drum template so they don't transpose, you just pick the key and scale your song is in.
I imagine PG would have a lot of musical Al Gore rhythms to work it all out, more than my knowledge of music.