One thing I do not quite understand from the posts here: With this wired up incorrectly would the ECAM show the correct direction of movement on the control check or not? When you do the control check you should certainly should check for both movement and the direction of movement of the ailerons.
There certainly have been cases of cross controls in older aircraft. I remember the China North West TU-154 which had the autopilot incorrectly connected. Unfortunately the flight crew elected not to disconnect the A/P and the aircraft crashed. However this possibility should be designed out of modern fly by wire aircraft. The fact that the wiring connections change for aircraft with different serial numbers with aircraft of the same type is a serious design flaw.