Incorrect structures in Desert Biome

Superflat Preset Desert

I see a very high density of structures, very close together. LOTS of lava lakes
I see inappropriate structures for the Desert biome, namely:
Witch Hut (Swamp)
Jungle Temple (Jungle)
Igloo (cold biomes!)

Also I think I am seeing incorrect passive mobs for the biome but can't be sure.

The world was created by 18w08b and I'm playing on 18w08b
At the time of posting 18w08b is no longer accepted by the Issue form, hence I am stating 18w09a above as the closest fit.