So, sorting is complicated. Right now, it's kind of a pain to add new ways of sorting because of the way the music wheel is structured, and the structure can't be changed without breaking theme compatibility.
However, I have dumped a lot of time into building
a custom theme that I started because I wasn't satisfied with the way song sorting works in Stepmania.
It has probably every sorting method you could want, and if I happen to think of a new way of sorting, it only takes a few minutes of writing lua to add.
Plus lots of other useful stuff. The downside is that I spend my time on features instead of graphics, so people tend to be driven away by the lack of fancy graphics.
Due to the theme compatibility problem and the amount of work involved, it will probably be a very long time before any advanced sorting finds its way into mainline Stepmania.