As Ryan says light wont directly harm the eggs but fungi seems to grow better with light so I usually cover the tanks anyway. You wont have hurt the eggs by having a look.
Have 50+ agassizi fry growing out now and had 150+ cockatoos from 3 spawns growing but they get to 20mm, just starting to colour up, bloat up and die. Lost over 3/4 of them in the last 6 weeks. It would be really nice to get some new bloodlines.