He could’ve, but he instead placed them correctly in Maya, then exported them with the appropriate rotation/location from a common center. That way, he doesn’t have to deal with aligning them properly.
But for doing that, he had to use 12 Button BPs instead (with a common parent BP that has all the logic).
If you use the same mesh, you can use the same BP; but you’ll have to position them correctly within UE4.