Looks like neither the green nor the red channels need to be flipped. Use the original normal map.
Use (0,0,1) Normal in WorldAlignedNormal.
For the remaining artefacts, you can use Blur2 mip blend setting and use LOD Bias of 1.
If you want better quality, then you need to check for normals that point toward both the camera and the light source using dot products. If so, then adjust the normal by adding those dot products multiplied together to the Z value of the normal and normalize.