This is as good as it gets with current version of CC. Indeed if I globally hide all those various normal effects in AE, it gets much better.
Once they are enabled back, the seams become more obvious. But you already know that



And it's not just one effect is faulty, mostly those for the face, when stacked up, are causing the issue and the more of them you apply, the more seams become visible.
It's just an imperfection in CC baking multi-layered normal maps.
So not really much you can do about in CC, unless taking out some of the effects at this point and maybe open a ticket in FT.
Hopefully in CC 4 it would get better.

The other way around, is to merge materials. I do not export to "outside" engines, but if you convert it to Game Base for instance (you'd loose polygons though), you can easily patch Normal map seams in Photoshop (because while merging a different UV set is created).
Which is what I did here:




Or may patch normal maps of the original model in Substance Painter itself. Not sure if that is possible though...