This is such a basic lack of airmanship that there can't be many excuses for the A340's crew.
Always check for traffic on finals before crossing a runway, even if cleared to cross. PPL lesson 1.01 or so...
That said, ATC has some answering to do too. I wonder:
1/ which language was used between ATC and Aerolineas Argentinas (if using Spanish then the approaching UTAir 767 crew was probably left out of the loop)
2/ whether any stop bars are fitted at taxiway/runway crossing points (such as M5 on the diagram).
I fly to BCN every now and then, and never like it. Convoluted taxi routings, near mandatory runway crossings (at least to/from apron R4), and you just feel that ATC isn't on top of their game. When there, I taxi at walking pace, make sure the FO writes down
all taxi instructions, and (yes, even before this happened) double-check all runway crossing instructions (and of course check for traffic).
I'll be even more careful in the future...
Cheers
