specific edge-case operation should not be trusted on the sim until verified and checked against aircraft operation
This is certainly true, but BEA has tested every steering input on AF447 against the real aircraft parameter and has come to the conclusion that they are completly consistent. There was nothing wrong with the way the aircraft behaved like this, it was the steering input that was wrong, i.e. they pulled too long and pushed too short. Simple as that. If they had pushed as long and as hard as they had pulled, the THS trim would have gone certainly back to a normal position.
You are hitting the wrong sack if you want to blame the autotrim. Autotrim is a perfect tool. They shouldn't have pulled into the stall.