As far as I understand this is the main cause, pilot errors came only after that
Think again.
The main cause was the crew attempting a stall manoever at low level and before that attempting a test flight without the proper precautions and briefings.
The sensor problem caught them with their trousers down, anything can be expected to fail on a test flight and you must assume that it will go wrong. That is what tests are about - to identify any problems.
Why do you think professional test pilots are a special breed.