e.g. A Pigman with Fireball enchantment will cast fireballs at player even if pigman is neutral.

Same goes to targeting - Enchantments with auto trigger (choke/alchemist/fireball/blastoff/...) should target only prey of mob, not any player within sight of mob

Same goes to spiders at daytime (even from mods), etc.

I know it was reported earlier, but looks like it bugs differently in multiplayer.

This is actually a minecraft bug of sorts - the mobs constantly target the player and drop the targeting immediatly, which unfortunately is enough to set off Infernal Mobs effects.

I think i fixed this for the current version of 1.12 (a target has to be targeteted uninterrupted for several ticks before a modifier triggers).