This is awesome! I'm a composer who likes to work with procedural tools, and this does a great work of creating melodies and harmonies that actually sound decent. Paired with the fact that it comes with three instruments, each with their own oscillators, filters, and settings - and this is actually pretty formidable.
I appreciate the Upbeat / Melancholy setting, though it would be nice to be able to select a key and scale (including harmonic, dorian, lydian, etc), even if that was hidden behind an "Advanced" option or something. Some additional MIDI generation options, like note density or lines of harmony, would also provide some nice control, though it's not too necessary.
This reminds me of InstaComposer, a similar plugin for DAWs. If this could export MIDI, potentially one synth at a time, or all three at once but in different channels, composers like myself could use it in actual music compositions by dropping the MIDI into our own synths and virtual instruments.
If you're up for it, I'd even suggest trying to see if you can make a drum machine generator. That would be really fun to play around with.
Overall, great work! This is definitely a very impressive tool.