Okay so I played around with that Google Bach Harmony AI today. It lets you download the harmonies it generates to your melody as a MIDI file, but you can only work on 2 bars at a time. So I generated the harmonies to a melody two bars at a time until I had a whole song then stitched all the downloaded MIDI files together in a MIDI sequencer and then imported that into Caustic (a Synth rack emulator for Android, Windows and iOS) and picked synth parts for the melody I wrote and the alto, tenor and bass parts the AI generated. Then exported it as a WAV file and then whipped together a simple animation for it in Daz Studio.
And here it is.