It certainly was for Joan. Don't forget Joan so-called "subjective visions" were a part of Reality.
Because I think this is an important issue, and because we're trying to be philosophically precise in this thread, I would word that slightly differently in order to preserve the very important distinction between subjectivity and objectivity. I'd say that what was verifiably real -- objectively real -- was a woman named Joan who seemed to be sincere, and who said she was having a subjective experience which she said were voices, and she acted in accordance with what she said her voices told her. We can never objectively verify the truth of her claims about hearing voices, but we certainly can verify her actions -- to the extent that anything can be historically verified. It certainly seems as if she sincerely believed she was hearing voices, and maybe she was; but we will never know.