predictorM9;
I suggest you have a look at
post #1817 AF447 Thread No.3 and check out the two links at the bottom.
The aircraft appeared to have a tendency to roll to the right, though this shouldn't have been due to fuel imbalance as that is equalized automatically. There is nothing in the BEA update to suggest a reason for the asymmetry.
Even with the THS trimmed 13° NU, the elevators will have had enough authority to cause a ND trim at IAS < 180 KTS. When that was done the stall warning sounded and the sidestick inputs were reverted to NU. The flight law was ALT 2 and the autotrim can be overridden by constant sidestick inputs or the mechanical trim wheel.
Once the aircraft had fully stalled at FL380, the AoA value was deemed invalid as the mean CAS was < 60 KTS. So you can see that after stalling they found themselves on the wrong side of the stall warning and didn't realize it.
Essentially the aircraft maintained >15° NU attitude all the way down and as the air became denser the forward momentum was reduced, the AoA increased while the RoD remained near constant.