As others have noted, blogs are not very good at metadata, and as far as I can tell the Intlligence Trainer relies on this junky data so the options are either minimal or outdated.
Instead, why not let us use our own keyword or phrase. In Focus, we would only see posts that contain that keyword or phrase. Even better, allow a string of these separated by a Boolean OR. Exclusions too of course by placing a “-“ in front of the search term.
This is different from saved searches because it’s not a separate feed.