Wishing, a friend of ours has chickens and she gave us 12 eggs, for our two little Serama broodies. Only five were fertile. This one hatched first, the second hatched, but died within a couple of minute and wasn't completely formed on back end. The third and fourth were 10 days past hatch and when we opened them, they were just dark fussy goo. The fifth was pecked open and just found an eye and beak, the rest was just sticky mess, so we think the chickens knew it wasn't going to form. I don't remember all that much about this part of rearing, from when I was a kid though.
I remember you saying this before, but as you will find out, my memory is strong as a steel sieve.
Seramas are awfully small for hatching large eggs. Broody hens will pluck their breasts so the skin is in contact with the eggs, which they turn frequently to even out the heat for the entire egg. After seeing my seramas hatch a few of their own eggs, I think it might too much of a difficult feat for them to regulate heat for large eggs. Although not for lack of trying. They are little broody monsters!