I was having a discussion with a co-worker who was a long term composite fabricator about loctite/superglue. He told me that when you are gluing plastic, the adhesive generates heat and can cause problems such as melting plastic, and I would also suspect the crazing problem you encountered.
He told me that if there is a risk of gluing plastic together and possible melting is to glue the items together and run some water over it until the adhesive cures.
Is there anything out there that will "fill" crazing or minor radiating cracks in plexi? Something that is thin enough to drop in around the screw head and it finds the paths to fill?
I'm not terribly worried about these on my rear window, but aesthetically it's hurts.