I personally don't think she would be stupid enough to defraud money donated to charity. She is so wealthy, it would have been a drop in the ocean to her. I don't think fraud is something she would be in anyway comfortable with, especially give her background in finance / insurance. I think she has convinced herself that her questionable sales techniques are all for the greater good - which they are not!!!! But I don't think she has done anything illegal. What she has done is more subtle and underhand, exploitation of loopholes and deceiving her followers. I cant see her 'justifying' stealing from charity.
A possible reason for not addressing, is because she has nothing to hide and there is no evidence. I think she would only relish in the opportunity of being wrongly accused of theft by tattle 'trolls' and then imagine the platform that would give her. I dread to think.
I understand not everyone will agree with me, and that's understandable. But I would advise you approach this matter privately with her firstly. Ask her the questions privately and give her to opportunity to answer privately. If so does, it will give a basis for further investigation and gathering evidence. If she doesn't, it will justify a more public campaign to highlight. I think this could be a bit of a trap, sorry.