Even Gonzaga's camp didn't try to claim those were downward elbows. They appealed based on the strikes being to the back of the head.
The rules should definitely be clarified, but your interpretation of them clearly isn't in accord with that of the fighters or the referees.
Yes there were many all sorts of degrees of elbows in there, from deep analysis and raping rewind buttons .. i m convinced two elbows that were really important for outcome (1 responsible for getting KOd out beyond repair) were indeed downvard, the one that caused Gonzaga's head to go into sleep position was a definite, and the one that caused him to buckle was also in the category of downvard in my opinion, of course mixed with "back of the head" as well.
Back of the head yes again the problem was that the whole thing happens very very fast with lots of emotions in there, there was also a big big mix of things and referee was confused what to do because everything was dancing back and forth of legal and ilegal, had not much time to think and it is much easier to judge after the match but this outcome brings many questions up about the rules and it will be interesting to see if other fighters start using elbows more and more.