What you describe is much simpler than being psychic. It's called guessing. Perhaps, as you say, she's very good at reading body language. If the story of childhood abuse is true, that may suggest why she wants to believe she's psychic. Abuse survivors often feel disassociated, like their body isn't theirs, or talk about feeling their spirit is outside of their body. And abusers often tell the victims they're worthless, so imagining herself with a special ability might help them cope.
This is exactly my own experience in the past as a young woman who had a rough childhood. In order to survive abuse I'd learned how to disassociate. Under the influence of the Seattle New Age scene as a young adult I thought something psychic and mystical was going on, when actually what was going on was PTSD symptoms. I even worked for a time as a "psychic reader".
People with PTSD from abuse can be hypervigilant. They can be good are reading body language, in that they are always scanning for possible danger. For survival we can cultivate an active fantasy life. Eventually we need to get proper help, definitely not from a New Age practitioner. We need to learn coping skills and how to focus ourselves safely in the here and now.
Ravenspeaker, the fact that students stay with her for years, and that clients endure long waiting lists - this is not at all necessarily a good sign. This could be a sign that people have developed an emotional dependency.
I, as a person who has experienced abuse, could never go to Char for treatment. Because she isn't licensed, she isn't supervised, she talks about her own abuse freely even in what should be a professional setting, and because her treatments are unsafe.
If as described in the book, she has locked up people who are psychotic, rather taking them to the hospital - this is very serious and unsafe.
A person may be charismatic, lovey, motherly, passionate, creative, they may believe that they are specially tuned in, they may honestly mean well - all while doing actual damage to their clients.
I may come across mocking or a little harsh earlier in this thread, this is because I'm from the Seattle New Age, I know the territory well. Whether a person is a con artist, a traumatized person dealing with delusions, or a mix of both, they need to stop taking clients and get themselves some help.