Phoenix, an interesting simulation; you focus your thoughts on trim. As yet I have not been able to find any reference to longitudinal trim in the report, nor in the FDR data; have I overlooked something?
Without accurate trim data the simulation would be meaningless.
For those who continue to debate sidesticks, coupling, etc, consider that trim is a powerful control system, which if inappropriately positioned can alter the apparent relationship between stick and aircraft motion.
In a conventional aircraft, a miss positioned nose-up trim requires a push force to fly level, and even more force (displacement) to lower the nose.
With a FBW system, there may not be any direct force relationship so the emphasis is on stick displacement. A miss positioned nose-up trim requires a constant displacement (off set) in the nose-down direction, the need for which may not be readily apparent considering normal operation with auto follow-up trim, and particularly when flying with protected systems and / or without stall training with the protections disabled.
For those who wish to look cross cockpit in a FBW aircraft they might better spend their time looking at the trim positon.
There may be similar issues relating to the rudder positon and trim. The ‘small’ rudder offset was probably limited by the higher speed cruise protection, but a greater range may have been available as speed is reduced.
Rudder trim was unavailable; the FDR indicates that the initial offset was not corrected manually.
This, and possibly a longitudinal trim issue, probably contributed to the continuous spiral descent, during which the wings remained in a stall condition.