Correct. She has been caught in at least two outright lies (fear of flying and option for Grassley to come to her). The only conclusion that can be reached is that if she has lied about those things it's perfectly legitimate to assume she's lying about others.
Another lie, directly about the actual assault was what she remembers the most. First she said her mouth being covered and afraid he would kill her.
Later when asked again, she said, it was them laughing at her. The third time asked she said the stairs, hearing them on the stairs and having to go down the stairs.