Since Aulani is on the "other side" of the island and on a manmade inland bay, I'd not expect the buildings to be compromised there. The first waves were said to not have much impact on the beaches. I think the reef will help on the Aulani side of the island.
The good news is that the Ko Olina Resort, including Disney's Aulani, did not suffer tsunami damage.
Please allow me to correct a few things in the quoted text.
First, the coastline at Aulani runs essentially north-south, and faces toward the west. That means that Ko Olina Resort faces Japan. (It's not "on the 'other side' of the island.")
Next, although Aulani is on a manmade lagoon, I wouldn't characterize it as "a manmade inland bay." It's not inland. It's directly on the coastline. The lagoons are partially open to the ocean ocean, and the barrier between the ocean and the lagoons is not very high. A "wall of water" could wash right over it.
As others have noted in this thread, a tsunami is not the same a high wave breaking on the beach. As the sad footage on television of the devastating tsunami in Japan showed, it's something very different. A tsunami involves a large volume of water.
There are coral reefs off the coast of Ko Olina, but I don't think they're the kind that would offer much protection.
Tsunami damage and deaths a long distance from an earthquake are a legitimate concern. Crescent City, California. Take a look at
Crescent City recalls terrifying waves of 1964.