I know nothing about PDF files, but could they be default fonts that are permanently embedded in the PDF file?
The restriction, by the book publishing source, Ingram-Sparks, is that ALL fonts in the book must be embedded. It's a standard restriction, but I've never had a problem with the same files succeeded with CreateSpace, so I examined the pdf file, and each of the two unembedded fonts (Arials and Times New Roman) aren't used in the document.
Instead, I suspect they're flagged because there are entries for certain formatting Styles which list "complex fonts" (which obviously aren't used anywhere, and are reserved primarily for foreign language usages. I'm thinking I'll need to abandon my use of the "Normal" Style and create my own (uncomplicated styles) instead of relying on the existing fonts.
A PDF file _must_ include a font, or it wouldn't display. Obviously its set up to use your system fonts to create the PDF output. If its a problem, you'll need to investigate what default fonts your particular PDF creator software is set to use.
All the fonts I'm using (and the only ones which need to be printed) are embedded. The only two which aren't aren't used in the source document (a WORD file).
I'm reluctant to permanently delete system/default WORD styles, as it's likely to prevent WORD from operating in the future when something it requires is no longer available.
I'm very cautious about my font usages, but I can't control which WORD defaults get included. At the moment, I'm guessing I've got to abandon the idea of using Ingram-Sparks, which has a bad reputation for being difficult to manage and requiring a LOT of low-level technical manipulation like this.