This is a lot to process. Okay, starting at the beginning:
I just tested all of CA and the tiles behaving badly still are wwee 04, 04 and 05. All else is well with that set.
PJ
I guess you meant 04, 05, and 06? Here's what the 04 and 05 tiles look like after import to Blender.

The wwee 04 at left seems fine. I compared several of the border vertices with the walk mesh from eeee 01 and they seemed identical. The only reason I can think of that there would be a problem is if there is a mismatch with the walk mesh of the neighboring tiles.
The wwee 05 has the walk mesh set at a very low vertical coordinates, but otherwise seem fine. This problem happened with several of the other tiles and I tried to fix it. Unfortunately I missed this one.
The wwee 06 tile is a muddle, with some parts borrowing names from wwee 03 and wwee 05. This causes the tile to appear inappropriately in the toolset. For example, it is using the name of the walk mesh from wwee 05, which would cause it to inherit the same set of problems. Yuk. I know from experience that this problem is real easy to introduce when you're building a mess of tiles. It's a matter of tediously going through every tile and making sure they all have their own set of unique part names.
Here's the updated tiles:
The older one has been deleted.