OIJ has released a little teaser with a glimpse of the project, check it out: https://youtu.be/pjgxKhF5IEo
I need to confirm this, but it does seem that the big glitching problem was in the end caused by the MIDI interrupts screwing with FastLED’s timing. There’s a temporary workaround in place now (an external piece of software buffering the MIDI commands and the code on the Teensy “pulling” in between frames instead of it running on interrupts.) I’ll take a better look at it when I’m settled in London next week and see if I can get rid of that. But it’s all running smoothly now!