Maybe when enabled this config, every mobs will target guards also.
Minus neutral mobs such as Enderman, they should only attack when provoked.

Why do you want this? I need an example. Making guards aggressive towards everything seems like a bad idea to me. They will attack known threats as well as defend from active (potentially unknown) threads.

Why? Golems do that and they are fine. When you have equipped your villager with the most op stuff, you would want them to fight every single hostile mobs there are.

Also I dont know if there are any mods with friendly hostile mobs for have this to be a problem???

Golems only work fine for vanilla cases. If a mod implements a custom creeper for example it will fail. I'll think about this.

Strange, modded and vanilla had implemented the "target all hostiles" mechanic in mobs as they pleased, why is this a problem with this mod? For the creeper example, the villagers should ignore attacking creepers, so of course the modded creeper will be ignored, but the modded spider wont.

And how would you ignore a modded creeper if it does not extend the creeper? Vanilla is allowed to behave wrong as it assumes a known, vanilla environment. And still causes issues: piglins for example are neutral towards villagers, they have no war, which makes sense to me. Yet piglins are labeled as Monster, which would cause guards to slaughter them without reason. (Like the golem does). I can imagine a lot of modded entities like piglins. I will discuss this issue and try to minimize incompatibilities before changing this.

I see, some mobs that are labeled as "hostile" aren't actuall hostile but rather, neutral, like enderman. The solution I got is a blacklist, one that can be edited and added, the mobs on the list will not be targeted unless they attacked a guard.

You can now specify you own list as well as attack monsters by default in the config.
If you want to exclude a Monster, e.g. the snow golem, you can enter it in the list with priority -1 to ignore.