I believe the US Supreme Court ruled a few years ago to remove immunity for "expert witnesses" against civil lawsuits. Don't know if this applies in this particular case and country, etc. However, if the GB felt she had hurt their case and had misrepresented herself (e.g. malpractice), there are US legal precedents to bring a lawsuit to recover costs and damages. Not saying they can or they will. But there are legal precedents of successful lawsuits against "expert witnesses" for malpractice.
At the same time, the main reason she is doing so badly is that she is defending and indefensible position. It does not matter how moral, educated, prepared, etc. you are. If you are defending the indefensible you look immoral, absurd, and clumsy.