Couple of things:
1. Small thing, but you might want to remove the second 'p' from 'enveloppe' (just a pedantic point, but the rest of the editor is in English, so…)
2. Have you considered some king of patch randomiser function? They've proved very popular in other synths (both hardware and virtual)
Also, do you have any plant to integrate any kind of librarian function into the editor in future?
Final question: will this work with Ableton Live, which filters out sysex and NRPNs? To work with Live, it would have to be able to connect to the synth directly, rather than relying on the DAW to forward MIDI data to the synth.
Keep up the great work!