I pretty much agree with your theory but I think there was more of a deliberate nature to the crime than purely accidental. The reason I think this is Casey told Lee that Zanny told her she was taking Caylee away from Casey because Casey was a bad mother. True enough but what is important here is that that was what Cindy was constantly telling Casey...and Casey resented it even tho it was true.
According to what Casey told Lee at the time, Zanny also told her she was taking Caylee away from Casey to teach Casey a lesson. I think this was Casey’s way of saying she was teaching Cindy a lesson.
Bingo - that, to me was a slip by Casey - her mother had called her that and I think she killed Caylee as a way to punish her mother for thinking it, and deep inside she knew it - Zanny said so
Quite possibly.
There's a line from a Pink Floyd song that keeps coming to mind: "You bought a guitar to punish your mom".
I think we agree that if in fact Casey did kill Caylee on purpose, it was to spite/punish/hurt Cindy and/or George.
My problem with all of this is that I'm not sure enough about "the event" to convict Casey of 1st degree, premeditated, death chamber murder. Also, I'm not willing to give the prosecution a "2-for" of child abuse and manslaughter for one event.