I've got two BSL, they are very sweet birds. Mine are very quiet and do well in confinement and get along with the other girls. I let mine out to free range at 6 pm and they will go back to the coop when it starts to get dark.
Those are amazing photos. Its sad they didn't make it, but its so very interesting to see what really goes on inside and what it really looks like. Thank you for sharing.
When we first got chickens we used to leave their coop door open 24/7 (we don't anymore). They would be right there waiting for us in the morning at our sliding glass doors waiting for breakfast. Scared the hell out of me a couple times.
I am very sorry for your losses. Everyone makes mistakes and it shows that you really care about your birds to post this so we can learn from your experience. I hope your little survivors pull through.
This reminds me of a post I read a while back about weird eggs. The pics look somewhat like yours. Here is the link, hope it helps.
https://www.backyardchickens.com/forum/viewtopic.php?pid=1006373