Is it simply impossible for me to not get errors and bugs with this engine?

[MrBigzy]

Yeah, anything below 3 or so would make it error. D:

This is because when he attacks, depending on how and what kind of attack it is (regular or a dash attack) his attack distance varies. The only way to ensure he doesn't hurt you and turns to smoke is to put the distance to 3-3.5 or above. That doesn't mean you can't make him disappear at 0.5 or so by trying to run into him while he's attacking, but if you're standing still or running away while he's attacking, he probably won't disappear.