Ill have to dig into that over the next day or so but a quick search provided me with this information
The accuracy of AI stylometry analysis can vary depending on the complexity of the situation, but generally reaches high levels, with studies reporting accuracies often exceeding 80% and sometimes reaching near 90% when identifying authorship in controlled scenarios, especially when comparing between only a few potential authors; however, accuracy can significantly decrease when dealing with a large pool of possible authors or when authors intentionally try to obfuscate their writing style
I did use known attributed material. On his twitter he links an essay he authored on christianity and the roman empire when he was 15. Here it is
https://x.com/pepmangione/status/1790617493956166115