Had breakfast, read @gloriouscow's excellent series on PC disk copy protection*. Seems like those weird FM mastering tracks with bad CRCs and long sectors might have been written by Formaster duplicators...
I'll have to see if I can get in touch with Scott Cronce or John Aycock and see if there's a formal spec for it. (at the moment Arcology only extracts the text strings)

*: https://martypc.blogspot.com/2024/10/pc-floppy-copy-protection-xemag-xelok.html
#digipres