A couple of thoughts have occurred to me (I am guilty of two things - much preferring the bus to the boeing, and instantly judging the FO when reading the BEA report):
1 Alternate law was not helpful.
When UAS is detected at high altitude, then maybe direct law would be safer. The stationary stabiliser would help the pilot keep the attitude stable. If he got slow, then he would need constant NU to hold the pitch - and the clue is there for him. Auto-stab is a nice luxury, but is best when combined with Normal Law protections.
2 The "illusion" of turbulence.
I have had nasty mountain wave twice - once in a Boeing and once in an Airbus. The event in the bus was a lift combined with a massive increase in speed. I had to disconnect, pitch up, and then dive when the speed vanished. By the end of the event I was more or less back where I started, save a slight bead of sweat or two.
Having felt that lift, might I (if I felt it again) associate it with a sudden overspeed? It's so easy to imagine UAS in smooth conditions. But what if the PF sees the speed indication go and then feel a huge lift? Pitch up because he has seen this before? Once he has pitched up, he has lost his "feel datum" because the stab is trimming for him. Still with no speed indication the confusion has set in, and there is no escape from the confusion.
It will be very interesting to see the plots. In particular G forces on the a/c and sidestick deflection. So much will be answered when these are available. In the meantime, more high altitude training, including dealing with various serious faults at altitude.
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Incidentally, I have been shocked at the number of FOs I fly with who have no idea of approximate pitch settings in the bus. They have all gone straight from Piper to Airbus, and have never had to fly by pitch. One of our Boeing FOs was chatting to me about this accident, and he could specify all the pitches for all phases of flight (happy memories!). As others have said, the bus is great but when it all goes wrong it reverts to a basic jet. If you have never flown a basic jet, then this can be a little confusing.