I have got an Ultimate 60 cc that obviously has one servo for each elevator half connected to two different receiver channels of my Aurora 9x. The problem is that when I tried to set and activate the snap roll function, assigned to a given switch, the elevator halves would move in opposite directions as if to make it work properly I had to reverse one of the elevator half.
I'd really appreciate if you could come up with the solution.

I spent one evening on the radio but I finally managed to make it.
The thing that I didn't get was that after having set the correct model configuration in the MDL Type page, the radio software acquired the ELEV 2 input that I assigned to the same gimbal as ELEV, of course, as if the plane had two separate tails, let's say like a canard plane.
In that way the "two tails" were in conflict with each other which made the Snap Roll function got stupid.
So when I instead assigned ELEV (not ELEV 2 this time) to the elevator gimbal in the CHANNELS page, things turned normal.
Well, I hope that this hint will help you Aurora 9X buddies to comprehend the brain of the radio.

Best thing you could do is forget about the "snap roll switch" and learn to do the maneuver. Setting up that switch will handicap you forever. If you do it, there is only one flight condition where it will work. One speed, straight and level, one direction.

The control inputs for a snap roll vary considerably from straight and level if you climb, change speed, roll in the opposite direction and so on. That switch is just a crutch that will keep you from learning the basically simple control inputs for a snap in all sorts of flight modes.

I absolutely agree with you, in fact I had never used that switch before with any of those natural IMAC like Extra's, Yak's, etc. until I came across this stubborn thing. That is also the reason why I am so little familiar with the snap roll settings in spite of having used the same radio for a number of years now. The switch got rusted inside and it wouldn't even return to its position now and then.
I just want to physically see, for my eyes on the ground, how much throw I should input to the control surfaces to make this Ultimate fly one single decent snap roll and then, starting from that point, adapting/adjusting the eyes-hands-dialog to it.
I am not sure it makes sense but this is how our hobby is all about in the first place.