Why not simply put a sequencer in with 32 tracks, or even unlimited tracks. Computers do this all the time. Although there is a 16 channel limit to MIDI I thought there is no limit to the tracks in a Type 1 SMF? Could be wrong, there, though...

It seems an awfully convoluted way to do things, when every sequencer program out there has no problem with 32 tracks and much more...

OTOH, who is doing full orchestral production on an arranger using the built in sequencer? Just about everyone that does that seriously has a computer DAW/sequencer...