I suspect the underlying function is designed for the 'less pro' versions of Magix software eg those that are used mostly / only in Storyboard mode. Agreed that there could be more flexible options but they might be beyond achievable programming.
I tried this in the Pro X6 version and it is the same as in MEP2014. No possibilities to do multiple transitions on tracks other than track 1.
It would be helpful if we could at least move the objects to an empty track, apply the transitions to the group and move them back.
I also saved a transition, Flying with a different name. It shows up on the transitions list but I cannot apply it. Did either of you try this? Maybe I just don't know how this works, but it seems to me that if I save a transition and it is on the list, I should be able to apply it.