Good question. Why wouldn't Charyse testify? Because the defense would have blamed her instead of Brandon. And they'd be right. She knew full well Juliette was being beaten. She likely beat her/them regularly.
I remember back at the beginning the babysitter said the kids were dirty and came in smelly clothes and that she often bathed them. Shuhreess was a poor excuse for a mother from day 1.
But could they indict her for murder/manslaughter? No, she has immunity, right?