If you consider the engine fault to be the cause of this delay, all 315 passengers are entitled to €600 compensation. If you add the other 315 passengers stranded in LAS that brings their cash liability to €378,000. That in addition to Hotac and meal costs, another 80-100K?
However I'm sure they will argue that it was an extraordinary circumstance due to US customs. (Methinks it would have been extraordinary had they done anything to help.)
So, the courts will have to decide, meaning it's the lawyers who will get rich.