One of the recent updates has made structures more affected by this mod. And I think that's pretty cool. But unfortunately, I've noticed that the structures just randomly choose which stone variants to use, and it's all in random patches similar to how the stone variants generate underground.

This results in structures that don't look right. So it would be nice to see this changed.

There's no randomness here. The stone variant follows the general world seeds. Sadly on 1.12, there's no easy way to have an homogenous variant for a given structure.
This is also affected by Aang23#218 which I have no clue how to fix...