How Santiago Calatrava was awarded the design for this is beyond me. The man has been sued so many times for leaks. He is known for a good visual aesthetic, but poor follow through.
IIRC there weren't many suits when he won the competition. It was quite some time ago, after all.
It's not really clear that the leaks are Calatrava's fault. It's not like these buildings are designed to leak, and architects have limited control over the GC and subcontractors.
Plus, when something goes wrong in a building, everyone gets sued, even "starchitects." It's mostly a game to wring money out of the insurers.
What Calatrava is
on the hook for are some of the inflated costs, as his designs are rather expensive to construct. Even in that respect, there were a lot of factors that drove the cost of the Oculus through the roof, such as demanding more steel in the structure, or Bloomberg demanding an accelerated schedule.