I don't think the majority of those who track you (e.g. retargeting advertisers) would need to track you for more than a month, that is, unless you are setting up your system or tweaking your IDE, it is very unlikely that you will change your set of fonts within that time.

Also, they aren't particularly picky about keeping you, the trackee, forever uniquely-identifiable.

Consider this: when was the last time you (the non-average) or your grandmother (the average) installed a font?