As you say, the crew appear to have done their jobs as well as can be expected of anyone. The primary issue appears to be the ige stall being at a significantly lower AoA than predicted.
The thing that puzzles me is that, if I am reading it correctly, they appear to have been conducting performance testing using the limit control force to rotate. This resulting in a pitch rate approximately double the normal.
Surely both from the point of view of minimising hazard and meeting the requirement to use normal techniques they should have been using normal rotation rates and ensuring the forces were below the certification limit. The maximum force test would come under testing the abuse case.
Sadly, doing it that way probably would just have resulted in the accident happening on a later flight when testing the abuse case, so not been of any benefit to the crew.