The crew has rushed and was clearly poorly prepared, but how would you want them to check those 3 AOA values when only 2 are available and so only indirectly through the third MCDU ... ?
I have no idea, I am a mere Line Pilot who flies A320s. If I was undertaking a formal test schedule requiring these 3 values to be recorded, I am sure my preparatory material would inform me how.
A CHECK GW MCDU MSG is certainly NOT a CLEAR indication of AOA DISCREPANCY
It should be to a crew doing a test Flight about to bet their lives on the AoA protections. For a Line Crew, I might partially agree with your comment.
AOA DISCREPANCY ECAM MSG could have been presented to the crew
I am not sure a Line Crew
really needs this - all it could really say is "don't stall" which they really should not be doing anyway
That said, I suspect some form of additional internal AoA cross-checking will be incorporated to address the latest OEB - if only to detect "frozen" values when systems calculate the value should change more than x?