With my paragon elf site, I think Phar can see perfectly well in here. it's twice as good as a regular elf's lowlight vision.Yes, there is enough light around the broken skylight (halfway between the two grates) to cast light equivalent to a light spell. The light beyond that is equal to shadowy illumination. So, 20 feet of light around the 10-foot opening of the broken skylight and another 20 feet of shadowy illumination beyond.
Also, any place where there are holes in the wall lets in a similar amount if light. The cracked and broken walls near the overgrown fountain let in most/some of the light from outside, as does the large hole in the corner of the eastern wall (with the rubble). There aren't any holes in the walls near the corridor, however, or along the great hall's southern wall (except for some small cracks in the southwest corner).
There are some holes in the roof 20 to 30 feet west of Aureus' position on the map.