Stylized Tree and Custom Normal

Hello, i have a problem on my tree, i would like make a stylized tree for my futur game.

I have create my tree with tree it, modifie the normal in blender. With a sphere i have use the Normal Edit modifier for match the normal with the volume’s sphere.

But when i add the tree to Ue, my render dosen’t match with the sun light, i have a litle brigness difference in the shadow side in the leaf.

This is particuliar visible in the case or two tree is in conctact.

I have try to use the vertex color for the AO but the problem is still here …

For the material i use the tangent space normal and TWoSidedSign node * const3 (blue) for normal.



I can disable the tangent space normal and put a const3 (blue) to the normal point in my material but the result is less cool … But the problem deseaper ^^