Hrm. Out of a whim, took another look at #Alacritty, and it appears to be working fine. I remember it wasn't doing something well enough out of the box last time I tried it. But now it does.
So maybe I'll switch to it? I'm using my own little, VTE-based terminal emulator at the moment, and it does everything I want and need. It doesn't need much maintenance - a recompile every once in a while -, but the less custom stuff I have to maintain, the better. So that tips the scale towards Alacritty.
Maybe I'll switch to it for a week, and see how it fares.