Okay, I ended up sifting through old prototypes to test this, and it works great. Solid backlight, smooth brightness transitions.
The project I tested was actually two of these displays with a single regulator driven by a teensy4. All the same...
Thank you so much—and thanks for offering to send me a board. I'll integrate it right into my current KiCad project - this helped me a lot. And it's funny—has this project always been there? I checked your GitHub and couldn't find it. Anyway...
I have an update on this: the pcb I ordered from my first pass at the schematic appears to work correctly! I ended up adding some jumper pads for IM* pins in case I had chosen the incorrect interface mode, but it seemed to work when I soldered it...