Comments like this are what the internet is all about! AFAIK Yugoslavs call tea "čaj" (pronounced... chai!). I have no idea about other Slavs. And if by Commonwealth you mean the British one, I think the biggest member state is India, where "chai" is also the word.
If the username is used as the salt when storing the hashed password in the database, it's unpossible to know if a supplied password is valid-but-for-a-different-account.
Some people, rightly or wrongly, feel that their use of an open source library is endorsement and thanks enough, at least until you meet the maintainer in person or have other cause to be in contact with them.
In some countries, downloading things from CDN has a significant effect on page load times so this is good advice. Sadly most users won't disable custom fonts because they don't know it's a problem.