Hi there! The GDM version's tiles are identical to the itch version's tiles. There are no north/south/east/west corners. By definition, the corner tiles may only be northwest/northeast/southwest/southeast. The directions refer to the two compass directions the corner faces, and those four corners are included.
This tileset is using my old export format- At some point I will come back and update this tileset to have a better / more usable structure, as I realize the tiles are currently difficult to use in tile-based editors (e.g. Tiled).