that's a surface shader... so unity is responsible from handling this. nevertheless: when it comes to light mapping all the shader does is to provide a valid meta pass. you can see the output of the meta pass by switching to "albedo" in the lighmapping preview (scene view). this should somehow fit a low res color preview of the terrain. it might be broken in 2019 versions of unity as the lightmapper provide corrupted uvs... nothing we can fix on the parallax shader – as it is a surfce shader. anyway: if the terrain is seen by directional lights then it should be see by point lights as well.