Some of the NZA airports add their own biomes, I think. It throws off the changes made by the 4 Seasons Mod. I don’t mind much; it’s a minor annoyance. For example, I flew out of the new freeware Raglan (NZRA), and was treated to a delightful display of fall colors around the airport. Unfortunately, it’s spring in New Zealand… It was a very small area, though – and like I said, I don’t really mind much.
Raglan is a grass field, so I can’t speak to any runway/taxiway texture issues, though. I haven’t seen any issues anywhere else, though.