I am sure they did their best and I am not even going to start with the subject. It is so easy to sit in your office and second guess things that happened earlier...
But, just as a point to the following statement:
"Bilbao is a CAT C airport, thus requiring additional training/familiarisation for the flightcrew."
Maybe it is CAT C, maybe it is not.
If it is not specially stated in a state AIP to require special training to meet certain criterias, CAT C airport determination is up to the operator.
Safe landings!