The subset of Markdown used in Retro doesn't really support any metadata declarations and isn't quite a full Markdown system.

I also don't want to tie my documentation too closely into HTML. Might it make sense to develop a more formal markup language for use with Retro & Konilo (clearly laying out what is expected and adding some well defined methods for adding data like titles and author)?

I don't think I'd make too many deviations from the subset used now, but having it documented and expanded in a few cases might be beneficial.