We wrote two Hebrew posts on the Mechaber’s opposition to the custom of Kapparos.
The skinny:
I just found Rabbi Meir Mazuz‘s Rosh Hashanah newsletter addressing this. He must have visited this site because I didn’t get it from him (joking!).
He has a different version of the number of editions with the title “Minhag Shtus”. More importantly, he attempts to deny the known fact the headings were written by the author by pointing to the language of one chapter heading referring to the third Shabbos meal as “Shalosh Seudos”, and another to “Birkat Levanah” as “Kiddush Levanah” instead.
My general impression of Rabbi Mazuz is the same as the Brisker Rav’s of the Rogotchover Gaon (from Making of a Godol). Their references, or footnotes, tend to fit into one of three categories:
Could well be \ Absolutely unrelated \ Impossible to refute
Here, our case is that of a clear description, while his examples are of cultural “translation”, or “adaption”.