I apologize for my quietness recently, I've been spending basically all my free time on this synth, and I haven't gotten a chance to do much documentation. The hardware is due in less than a week, so I've been under a lot of pressure!
Here is the front panel PCB with all 600+ LEDs on. (Actually, they're not quite all on, due to another part of the software I forgot to disable while running this test--but the other red and green LEDs in the central matrix do work).