Uhm… its really funny, but i guess not intended? 
I don’t really have the time to test if this happens only with sponge and so on right now, maybe this is even already a known issue or fixed… But if not, maybe someone can test this and post an issue on GitHub? ^^
(if it matters, the world got generated with this code)
Maybe the generator is mixing seeds or biomes from multiple worlds or something?
This sort of thing is sadly rather common with some WGen mods, such as Biomes-O-Plenty or TerrainControl, and can also be exacerbated by some village-tweaking mods. I’ve never seen it happen in vanilla. It may be worth checking if it has any options for control over village placement, or if they can be added.