Shading artefacts

About the inversion, you forgot setting Location Y = 1 on the mapping node.

What I mean with large-scale is that, the normal map e.g. seems to try to change the shape of the lips, making the curvature sharper. Might be it was baked from one subdivision level to another or so. In any case I believe it helps to get rid of that. If you look at the normal map, there shouldn’t be any big streaks, only the soft bumpiness. If you look at this image again

do you see the ‘strength’ of the normal map (deviation of the color from the background blue/pink), e.g. at the tip of the ear or on the eyelids? What you should have is the soft pattern on the top of the head and down the neck, but not the normal map messing with sharp features of the geometry in this way.