As to the DT referencing any of that part of the 911-call testimony, I think they knew well that "Daddy" = dynamite. They absolutely had to stay away from that -- I think the "Daddy do" and/or "Daddy did it" in both places was certainly discernible by JY -- it was his own child; he had heard her speak and say his name hundreds of times, I'm sure. Don't touch that evidence with a 10-foot pole.
And, glee, I agree with your take on CY's acting differently at the Center -- I think the little girl was clearly trying to sort out what she saw that night. Was it a bad dream? Was it another one of her parents' shouting matches? Did Daddy have to spank Mommy for biting somebody?
I well remember when my son was little and we were talking about Daddy being sick with a stomach virus, I think, and my son clearly said, "Well, you're his mommy, too." And that little statement really hit me as to how he looked at the family dynamic at that young age. It gave me such an insight as to his very simple and loving view of his world.
As soon as I heard and saw the Daycare teacher's re-enactment testimony, that's exactly what I thought back on -- my being "his Mommy, too." Again, out of the mouths of babes -- "husband and wife" is not a concept that they can grasp at that age -- it's all "me, mommy, daddy, brother, sister."