How about a text based UI? Like a console of sorts. The sound designer would tell Synthmaster commands and program the synth that way.
volume 80
oscillator basic square
lfo 1/4
mod lfo adsr 70%
oooooooooooooooooooooooooorr something like that, with command/options auto-fill. The "terminal" would show history with older commands as hot links to edit with one click.

