Can't feel any sympathy for the head maid. She claimed to be faithful to Aaduo, but her actions were all self-serving, and caused pain to everyone around her. Including the lady she claimed to serve.
But there is one thing I don't understand. When did she realize it was the honey that killed the child? She fed the child food that was deemed safe, and then the child died of unknown causes. Maomao even says "what you didn't know though is that honey [...] could still contain small traces of poison". So why would she think after the child's death that it was her fault? Was it after Rishuu shared with her the story of her getting poisoned by honey as a child?
Because here is where her actions becomes completely self-serving. Lady Aaduo, who could no longer have children, found an adoptive daughter in Rishuu. They both cared for each other. But to protect herself from Aaduo possibly learning the truth, she also drove away her adoptive daughter. She took away a tiny comfort she had found, just so she wouldn't learn the truth. And when the risk once again showed up, she aimed to murder the girl instead.
I guess it's maybe better for Lady Aaduo to believe her closest friend tried to murder someone she cared about for the sake of her position, than to know she did it to cover up the fact that she also killed her first child.