Programming

That's...actually a substantial amount more latency than I'd expected. Not exactly the same thing, but for perspective, while I haven't played multiplayer competitive FPSes for many years, back when I did, the limit of what I could really "feel" when it came to network latency was around 10 milliseconds. The latency the keyboards are adding, if it's as high as measured, is a really substantial amount of delay to be adding if you're talking video games.

considers

Note that depending upon the keyswitch mechanism, the controller does need to debounce the thing to avoid duplicate keypresses. I've used a keyboard before with a controller that didn't adequately debounce, and it was extremely obnoxious

occasionally would get duplicate keypresses, and I had to filter it out at the level of my computer.

However, if you look at gamepad button latency, they also need to worry about bounce, and their latency is much lower:

https://gamepadla.com/

You can get gamepads with sub-2-millisecond latency on USB.

EDIT: Note that one thing that I learned from following !ergomechkeyboards@lemmy.world is that there are some semi-standardized open-source firmwares for (fancy, expensive) microcontroller-based keyboards; I believe that QMK is popular. I don't know how the latency on those microcontroller-based keyboards compare, but assuming that there aren't any fundamental constraints imposed by the other hardware on the keyboard, it might be possible to shave some time off of that by tweaking the firmware.

I believe that at least some keyswitch mechanisms become more prone to bouncing over time, but if so, it might be possible for a microcontroller to detect bounces and tune the wait time to the mechanism on a given keyboard to adapt to mechanism wear.