Do the NPC spawn on their own? If so, where? Because i've playing for a while and I don't see them spawning. I also tried installing Sokomines' Villages mod, and NPC don't spawn there either. I think it would be perfect to have the experience of Villages with NPCs once and for all in Minetest.
NPCs are set to spawn on brick blocks next to a grass_3 node, which is quite specific but done on purpose. Igors will spawn on a meat block next to a brick, and Traders have their own spawn shop blocks.