polygraphs are not accurate enough to be used in a “legal” setting such as this.
If the accuser is mentally disturbed, she might actually believe her own story and pass the polygraph test.
Ana Montes, absolutely guilty of spying, evidence was Bountiful in her apartment yet Ana passed every polygraph test given to her. How? There are some physical things that you can do which can alter your physiology just enough during questioning & will cause the polygraphed to have a false reading.
https://en.m.wikipedia.org/wiki/Ana_Montes
This is not a legal setting; this is theater.
False positive poly results are common with Catholics and Mormons.
Databank of poly operations and training.
https://www.antipolygraph.org/
And the US government conducted a true scientific study of the polygraph and find it useless (National Academies Press). https://www.nap.edu/read/10420/chapter/1