They seem to have reversed EVERY non-symmetrical letter. I wonder if there was some sort of engraving system involved, where an inscription in one clay tablet could be dried out, and then pressed on another clay tablet to copy it.
This link implies that (at least sometimes) archaic Latin/greek was written right-to-left. The hardened engravings would travel better, but be reversed, while the soft clay ones would be considered more disposable.