Chris, can I pester you with a couple of questions? I've got Webmention/Semantic Linkbacks mostly functioning, though as you mention there's a gravatar issue; not only are gravatars not being pulled, but generic ones aren't being generated either, with the result that if I turn gravatars on in the Webmention settings, I wind up with a bunch of white space where the links should be. So I guess question 1 is... is there anything that I can do about that?

Question 2, though, is about the ways that mentions are appearing. If you look at https://kfitz.info/why-not-blog/#comments, you'll see that the first comment is me on Twitter; that one was pulled in using the old Twitter Mentions as Comments plugin. (That plugin has apparently been abandoned, and so I've deactivated it in favor of the solutions you describe.) The next two comments are replies to my tweet. Every other tweet that has linked to the post has been treated as a mention rather than pulling the tweet in as a comment, and the mentions link to the authors' websites as listed in their Twitter profiles, rather than to the tweets. Is that expected behavior for the Brid.gy/Webmention setup?

Thanks for helping walk me through all this. I've been fairly deep in the Domains world for a bit now, but this has been my first introduction to the work being done by IndieWeb!