Continuity mistake: When Wendal is saying about an uncle who runs a crematorium, the hand he is holding the bones in changes between shots. (00:07:00)
Revealing mistake: After speaking to the children the victim used to look after, the scenery outside the car shows the car is going forward when we see Booth but when the camera is on Bones, the background is going backwards. (00:17:50)
Answer: Since the palatine bone is a bone that helps form the mouth it has a lot to do with speaking. The shape of it differs a lot depending on your ethnic background. I would guess that they, in the show, meant that the person's bone tells that they were Japanese and that it was "made for the purpose of speaking Japanese." That's what I'd assume anyway. I've studied molecular biology though, so I'm not an expert on bones.