I figured I would follow the instructions and thought that the .imazingapp data was correspondent to the iPhone you pulled it out from and could not be interchangeable, nevertheless I tried your suggestion and used the .imazingapp from the 6s and restored it to the XR. As expected none of my game saves were transferred. Is it possible that something changed in IOS 12.1 ? because I have heard this works in IOS 11 and did it this myself when I first started to play 6 months back. To answer some of your questions, Facebook most likely is because I was logged in fro my original save, so I assume it moved over as well, I can login with my game tag and play, its just none of my 3 character saved games are there.
On a side note... I have verified that the 6s .imazingapp backup is good and has the game saves, I deleted my game on the 6s and used the .imazingapp file and it restored the saved games.