The tag name is just a regular name that has been defined or imported in the namespace. So the discovery process of what is this tag string and how does it work, starts there. So I would imagine someone in a code editor could click on the specific regex name for the tag string, go to its definition, read its docs, etc. Code editors could also usefully summarize usage as well through hovering.
Tag strings are often stringified, or return subclasses of str, but not necessarily. We didn’t want to deter the innovation that was possible by returning other objects, and especially provide hard edges that would require someone to go back to using sys._getframe for their actual problems.
Given the use of backticks in JS tagged template literals, it was the first approach we considered for Python. But each of the current string variants, especially f-strings, required understanding of this new syntax. Starting with the same syntax as f-strings, but targeted for DSLs, seem to be straightforward to teach and learn.