Did the eggs die early in the incubation for some other reason than "over calcification"? If so, that could have been any number of reasons. From what I can see in the pictures, the eggs look pretty normal to me. I think this species, like Drymarchon, make pretty thick eggs. If I were concerned that the babies could not cut out, I would definately cut all the eggs as soon as I saw one cut. Hopefully in your experience the babies that made it through full incubation were able to get out and make it. Good job with your success.

ECTimaeus