Did Princess say these buses were lift equipped? They have told us before that transportation was "accessible" and then we found their concept of accessible was "only 2-3 steps" and able to carry your wheelchair in the luggage compartment!!!! Call them back and confirm that you can get into the bus without having to take any steps at all, and that it is lift equipped.
Curacao is a nice port. If you can't get to the Seaquarium, it is an easy town to stroll around in with a wheelchair. Some curb cuts, and most shops level or only 1 step, which we can manage with our manual wheelchair.