Well, I'm sure displaying all the correct GGL benefits is really very important. But the booking engine doesn't recognise many of the destinations that oneworld airlines fly to as also noted upthread - I just tried Lima-Trujillo, and suggsests I fly to Tegucigalpa - that's only 1600 miles away, and arguably in a different continent. I am sorry, but a new page that doesn't allow to book these sorts of flights is a really big failure.
Surely that is a really important piece of functionality that should be working.