I believe this is an early version of the Sephardic myth from the family tree of Rabbi Eleasar Fleckeles (1754-1826) of Prague. The second paragraph on page 388 discusses his ancestor Moshe Chaim Todros (1634-1709). It comes from a handwritten document from the rabbi found and published in 1893 by David Kaufmann. Kaufmann, Der Stammbaum des R. Eleasar Fleckeles, Monatsschrift für Geschichte und Wissenschaft des Judentums, Jahrg. 37 (N. F. 1), H. 8 (1893), pp. 378-392).This would be earlier than the similar reference in Koppelman Lieben's 1856 book Gal-Ed, p. 47, nr. 83b.The source for both may be Megilat yuḥasin by Moshe Meir Perles (1666-1739), which also contains quite a few errors regarding the genealogy of Rabbi Loew.We discussed this issue in an earlier post at https://www.facebook.com/groups/TheSepardicDiaspora/permalink/2172061446386818https://www.geni.com/people/Rabbi-Moshe-Todros-R-Eliezer-s/6000000000348813413