Another issue is copyright, which for typefaces and fonts varies considerably by jurisdiction - using Google seems to offload liability as long as you use it within their terms then they should at least be the leading co-party if a rights owner sued.
Do you have a source for this? IANAL but if a Google font was disallowed for a jurisdiction, Google would be in legal trouble for advertising/hosting it on their own site, but that would be a separate case. I seriously doubt they'd share any of the liability for you using it on your site.
No source, just a feel for it as I've studied quite a few copyright cases.
I guess it's like me having an embedded video except that for the fonts Google have uploaded the media, not the public. If I watch a video on YouTube that was a copyright infringing upload, strictly (in my jurisdiction), I would have also committed infringement. But the courts are exceedingly unlikely to punish me, especially if the uploader warranted the video for my use.
That's an implied warranty, I should do due diligence, but if they have doubts they should temper what they say too (they probably attempt to disclaim the implied warranty in their Terms). If they're offering fonts that are not "open source" they are in the wrong; I might also be wrong but I should - when using the fonts as they direct - be able to sue them in turn if I'm sued for using the fonts they offer.
It's not joint liability, but in general the law accounts for people being deceived. It's not negligent infringement on my part, IMO, as I checked the Google info for the license terms and have no reason to suspect they're wrong.
If the BBC put on a tv show they don't have copyright permission to air, and I suggest in my magazine article that you watch the show, I've directed you towards infringing material - which may be contributory infringement (in UK) - but the BBC would be the principle offender. If the BBC make statements saying the work is free-libre, and I rely on that then to me they appear severally liable, and liable for deceiving me.
