Book 16 says the original homeland is not first the place of birth. It is the place where God can finally settle, have a family, and share ordinary life with humanity through True Parents.
That gives homeland a relational definition. The truest homeland is where divine and human family life can actually begin and remain.
This is a useful bridge note because it turns homeland from abstraction into settlement. People are not only searching for correct doctrine. They are searching for a place where God can stay.