Use structure blocks to modify the original textures in a data pack, so each time you generate a new village in a world the buildings will be replaced by yours.
The villager entity has a unique set of spawn events that can be used in Minecraft commands such as: /summon and /event. (The spawn event parameter is called.
In Java Edition, old villagers can only spawn in versions of Minecraft prior to 1.14. In Bedrock Edition, old villagers can only spawn if they existed from a.