A bit surprised it was on the high end, but I guess I shouldn't be. I created a separate, more minimalistic HUD for lower resolutions, which I'd observed were a problem from interface elements being squished into each other. But I'd never done any testing at higher than 1080p, because that's my monitor. I'm guessing I did some approximate math with the text wrap that isn't close enough at very high resolutions.
The change between right/left mouse buttons was a button on the screen like the lettered shortcuts (which also indicate the keyboard key, V can turn them off if you remember those keyboard controls). But I apparently phased it out at some point, and have it in the options menu, which is unreachable without a keyboard anyways. So there's a mystery for me to figure out.
Also, the T key is supposed to lock onto a target, but I just tried it and it crashed the game, so that's a whole thing to figure out too. Really helpful to find these things.