I'm not sure who is at fault here - like most accidents/incidents no one person or organisation is completely to blame.
What I will say is that taxiing an A346 is more difficult than you think. Taxiing an A346 around 120 degree turns without markings will not be much fun.
I have taxied the A346 around places like JFK and it doesn't matter how many cameras you have - it is very very easy to get it wrong.
I am curios though as to why they are so far off the pavement.
W2