Mysterious Asteroids Deluxe "deterioration"

[pseeds]

Could the PCB's ROM error that it's reporting be related to this problem? That is, is it possible that I don't need to replace the chip at R2, considering the error appeared right before all the capacitor problems began?

Certainly possible (IMHO). Power issues can cause weirdness (my experience). That is why normally one starts with the power section of a game and moves out from there.