There are two different cache folders you're dealing with.
In AH2 itself, there is a cache folder with the same name as your terrain. If you make any changes to the land tiles you need to delete that.
In the TE, if you open another terrain than your snow terrain and work on it you will most likely wind up a weird mix of tiles. Delete all of the files in the TE's cache folder every time you work on a terrain that's different from your snow terrain.
Also, every time you rebuild a terrain you need to copy it to the AH2 terrains folder. It is only written in the TE terrain folder when you rebuild it, not into the AH2 terrain folder.