From the look of the of normal map, HeroEngine appears to be rendering as I would expect. I see anomalies in the map consistent with the odd shading on the model. Am I correct in thinking the maya screenshot is of the hi-poly model?
It looks like you've mirrored some of your UV's, correct? If you have overlapping UV shells and try to render a normal map it will produce incorrect results.
The screenshot is of the low poly model + normal map actually. It does look as it should in Maya.
I mirrored some of the UVs but they do not overlap, all identical UV parts are above the 1,1 layout as seen in the attached picture, a method that does work with the hard edges areas of this very mesh and also works with our character, although, having checked it it doesn't seem to mind having overlapping UVs either. normal map looks just fine on hard edged areas, and in any case, one side should look right while the other not if that's true.
Those anomalies are simply how Maya or XNormal bake the high res mesh on top of the low res mesh according to normal angles which in this case are different from one area to another.
I guarantee that if I delete all the duplicated areas the problem would remain

Perhaps HE can not handle meshes with different normal angled areas?