I was intrigued and had fun seeing the combos in the customizer. It would have been nice too for those who like to know if it informed you of the fonts used.

It did work when published on my 2 test sites, wondering if it is because both were child themes (wild guessing) or it is the parent themes I have (one site is a child of an old version of Cover https://wordpress.org/themes/cover/ and the others a child of Anders Noren’s Radcliffe)