You may be able to find an email address on the GH page. I think that’s about the least invasive way to report an issue.

I have similar privacy concerns. I email authors / sites when they have typos. There used to be a blog that required having an ex-Twitter account to contact. I never was able to let them know when they had mistakes. In my experience, most authors appreciate a heads-up to correct a mistake, so that was kinda painful for me.