Structures will generate despite not being related to that biome. I explored for a while and found some structures such as a shipwreck, igloo, and jungle temple. (the village is normal)
The desert temple I found was deep underground which is extremely strange.
Steps to reproduce:
1. Click create a new world. Set the world with the preset "Tunneler's Dream"
2. Go to the text box located at the top of the screen.
3. change ";3;" to ";1;" and add the tag "village" to it. Should look like ";1;village"
note: only changing 1 part of the text. not the entire thing.
4. Create the world and use the /locate command on either an igloo or shipwreck.
Requires structure generation to be enabled.