I wonder how the Japanese species is doing in the USA. My next door neighbor has a Magnolia. It's a huge tree for hot climates with big white flowers and thick leaves.
So far as the climate is appropriate, the foreign species can survive and flourish. The magnolias commonly seen in Japan (Magnolia quinquepeta or Magnolia liliiflora) looks different from those in the States or in Europe.
Do you happen to have any image of the magnolia in your neighbor?