First thing that popped into my mind when reading Plaintiff's previous brief:
"I don't remember them arguing that. What are they doing?"
The new Appellant's brief has a point: Plaintiff suddenly switching from a nonfeasance argument (failure to act), which the original trial entirely revolved around, to a misfeasance argument (wrong resulting from an affirmative action) is a big shift, and probably a mistake IMO.
The evidence for misfeasance is much shakier and more scant than the evidence for nonfeasance, relying solely on inferences from second hand testimony that is directly contradicted by other testimony. It wasn't even well fleshed out in the original trial briefs and was barely touched upon. Why Plaintiff would want to switch to this strategy and give up her advantage I have no idea.