Rotation Control Over Tiled Animation Tiles

If I draw tiles in that have multiple keys/facings, then fill them with a simple animated tile (in this case, the waterfall bottom from the sample project), the animated tiles then take on a rotation based on the previous tile (or so it appears).

Example:


I imagine this has something to do with the Tile Orientation Matrix, but I was wondering if that was correct, and if that can be edited via C# script (since it's currently not editable in the UI).