Three things I've noticed using this mod.

1. It overrides the games rules on where things can be placed. I copied an area with a foundation without making the new foundation in the paste area, and it still put down the indoor-only concrete flooring tiles. The game still recognizes them as being outside, so I can't put other indoor flooring or items over them, but they are there.

2. It puts down stuff that is already there, which I think is another part of the first issue. My copied area had an outdoor courtyard & the workers put down dirt on every tile, even though there was already dirt. it did the same thing with the existing permiter walls I had up.
*Edit: it does charge you for them again, I checked.

3. It seems to hijack priority. While my workers were working on the pasted area, they would not work on anything else - even if I set it to Urgent.