"A hui hou kāua."
Translation:Until you and I meet again.
So is it implied that "A hui hou" includes three or more people unless you add "kaua", which would make it two people?
Yep! It's just a case of not every translation having been added to the list of answers, especially with the course being in beta. I would say you could report that as "My answer is correct" and a contributor might add it to the list of accepted translations! :)