I believe the whole point of this arc was to show how delusional — if not dishonest — Boopsie is about her claims of past lives. She claims to have been Harry S. Truman, even though Boopsie’s and Truman’s lives overlapped each other. Then she was a fictional character. Now, she claims to be Catharine of Aragon. Catherine of A was not beheaded. Her life also overlapped the life of the 6th wife.