Don´t get confused about the term SpecularProbes, that is just the name he created for this script, but it really is just Unitys reflection probes.
He does that, because it seems, that Unitys reflection probes could not capture those bright spots from the point lights, to get those highlights in the reflections. So he bypassed it by spawning glowing spheres around those point lights, which then would be captured instead of the original point lights.
Unreal reflection probes will capture every static light source (scale the size of the captured light via its “Source Radius”) and every static object, so you would not need to spawn in additional spheres or geometry, to capture their intense lightsspots. But it might be easier to just capture glowing objects to get the look, that you want, since those objects might be easier to handle and scale, than the lights.