cfx seems to relate to special effects used on the map. For example if sand is blowing on the map or if snow is falling, etc., if you're reading this you should know what I'm talking about.

Not much else to say but at the end of the water31 file I saw what looked like it might be uncompressed TSA or something, but it's just a hunch. From the 15 seconds I spent looking at everything in this folder, I'm going to assume all data pertaining to the effects is within the files. The files are pretty big, so that'd explain something. :P