ah you’re right it is hiding a bit… I went through the process of regenerating my twitter feed to find it, but you don’t need to do that. Just change the url from starting with: https://twitter-atom.appspot.com/atom? to: https://twitter-atom.appspot.com/html? to get the microformats version.
thanks for the feedback as well! Having context above or below sounds like a good setting to add so that people can choose. Happy to look at why your OPML didn’t finish importing… is it a public list somewhere I can look at?