Maybe this is a dumb question... but I dont find any option to turn a village I've customly made to a village that can be used and guarded by these npcs. It is a shame cause I want to make a roleplay-adventure server using this mod and the FTB mod, but creatures can spawn in the outside of the village and I want some guards defending it. I've read the option "turn back to village" but, how I make an npc understand that the village I created it's his village? Thank you.

I too am wondering! I don't know what specifies as a "village". thought it was a bell, and I was hoping my NPCs would walk around the spots of town with a bell, but they just wander aimlessly.

Thanks for the feedback. Basically the NPCs using the Villagers and Iron Golem goals, so as long a village is near by it will use this village. You can locate the nearest village with /locate #minecraft:village.

In general a village has some specific requirements like:
https://minecraft.fandom.com/wiki/Tutorials/Creating_a_village

With the next navigation update I will add the possibility to patrol or walking around a specific point.
This would allow to specific the "home" for an NPC without the need to have a valid village.