Hi Es,
The whole situation is so sad.
There have been times when she was having real doubts about the Organization. When I saw glimmers of hope that she might get free from it. She said things like "Is it my fault that Armageddon hasn't come and we've all been had?" and then later outright denied she ever said them.
Because of the doubts and what your sister said, there is a good chance that she'll come around. I pray that she doesn't let years pass before she does. We can't go back and replace lost years with family.
peace,
somebody