Every single 3rd party font gives me validation serious errors
I've been having the same problem. What has worked for me has been to install an app called Typelight. I go into Typelight, open the font that I downloaded to my computer but didn't install yet, and then save the font to my DESKTOP. It doesn't work if I save it anywhere else, don't ask me why. After that, I open the font by clicking on it on my desktop, then I click "install", and it works with no error messages. More of a hassle, yes, but at least it's a way around the problem.