Normals map vs light source direction

Normals map does not behave correctly on the opposite side of the light source.

I am wondering if there is a better technique in general for blending assets with the landscape, or maybe there is a node/s that I need to be using in the material to make this work correctly?

As my screenshots illustrate, right side of the asset, the side that is facing the light source is blending with the landscape perfectly fine, but the opposite side has it’s normals inverted.

Asset outlines.

Unlit screenshot demonstrates that textures match perfectly.

I am using a custom Material Function that projects textures vertically and helps match asset’s textures with the landscape.

Here is the Material Function.