Many, many people, including artists, writers and musicians, have given a false history of themselves. Grey Owl, a writer and early conservationist, claimed to be a Native American. He was actually an Englishman called Archibald Stansfeld Belany (1888 - 1938). And the writer Patrick O'Brian (1914- 2008) invented a whole early life for himself. This didn't stop him from producing a series of outstanding naval novels.
Yes, BSM was wrong to accept awards that she was not entitled to. But that should not detract from her outstanding artistic ability.