The Google Font FAQ includes the question: What does using the Google Fonts API mean for the privacy of my users?
> "...your requests for fonts are separate from and do not contain any credentials you send to google.com while using other Google services that are authenticated, such as Gmail."
>"Google Fonts logs records of the CSS and the font file requests, and access to this data is kept secure."
So a lot of fluff and no actual reply.
Users can be tracked without cookies being sent, while "access to the data is kept secure".
Call me a cynic, but I lost my trust in google a long time ago.
To answer "track users across different websites", I think they pretty clearly say the opposite:
> The Google Fonts API is designed to limit the collection, storage, and use of end-user data to what is needed to serve fonts efficiently.
> When millions of websites all link to the same fonts, they are cached after visiting the first website and appear instantly on all other subsequently visited sites. [...] The result is that website visitors send very few requests to Google: We only see 1 CSS request per font family, per day, per browser.
I guess, what would you want to see that would assuage your concerns, beyond what is written in the FAQ?
The Referer header will leak what page you were on and you probably already have connections to Google from the same client IP address. Even if you have Referer blocked, the particular font requested could indicate information about what page you are on when combined with other data.
Multiple people (I know as my upvote just now didn't even get you back in the black) downvoted you (and now me ;P), but you are absolutely correct that that quote didn't really have anything to do with the question.
No. A font file served from your own server is just like any other static asset. (I increasingly tend to do this for my sites, as I've found that using FontSquirrel to create WOFF/WOFF2 files that contain subsets of fonts and/or "collapse" font features -- e.g., stylistic alternates -- can make for very small, efficient files if the subsetting meets your needs.)