I have found a couple eggs under the roost too. My girls were new to laying as well, but it sure is frustrating to find and egg under there with all the poop. I had an older hen start to eat one that must have broken when it fell, I was really nervous that she would start to eat other eggs but never noticed it and now the older hens are gone so I don't have to worry about her teaching it to the others.
They'll eat a broken egg if they find one -- it doesn't mean they will destroy eggs in the nest. When my Maggie was roost-laying, three eggs bounced and two cracked. Then, I also had a hen start laying soft-shells due to stress from worm infestation and a couple of those were dropped from the roost. No egg eating behaviors arose.