Hi Sean,
Some are from the System, others no. My test file have 3 lines :
— the first one is an System OpenType font : Charis SIL ;
— the second one is a System PostScript font : Alegreya ;
— the last one is a math formula in CMR fonts.
The second line is composed with private TeX Alegreya font.
1/ The pdf is correctly displayed by Apple Preview and Acrobat Pro even when these fonts are not installed in the System.
2/ Illustrator CS6 + El Capitan (OS X 10.11.6 without these three fonts) does not recognize Charis, vectorize correctly Allegreya et does not recognize CMR fonts (see above).
Why this difference of behavior between Affinity and Apple Preview + Acrobat ?
If necessary, I can send you the pdf file (32 Ko).