I’ve had the chance to play this mass at our new parish for a while now and I think I have the hang of it now. The backings I made for it here are pretty average and the Sanctus is much too fast in my backing so just ignore that.
The music is rather subtle and I like playing it on guitar because it has lots of interesting chords and rhythmic invention. Its weakness may be that it can get stomped all over by an assembly and lose all its nuance. Perhaps this is a mass for small assemblies and minimal accompaniment.
I think these backings for the Gloria and Holy Holy are less terrible.