For some reason, the first time I tried to run RTST after updating, it caused PS2 to crash on launch. Since then I've been able to get it working consistently as long as I have RTST running first. I tried loading the HUD component and it appears to be working as expected.

Regarding the error prompt, the only thing I didn't mention is that it only appears after PS2 is launched successfully and RTST first displays something in game.