[sciurius]

I try to understand...

What we refer to as %TITLE% is, in fact, the sorttitle. Okay. Perhaps this would better be named 'displaytitle' then, the other being 'sorttitle'.

You have no problem to display the formatted title, while sorting on the (sort)title. For example, when I put the composer in front of the title, the library screen shows the entries sorted on song title:

AAA - Song AAA
BBB - Song BBB
AAA - The Song CCC
BBB - Song DDD

(Provided I uncheck 'Use formatted title for sorting')

Isn't this what you mean with "Having something that starts with "A" show up under the "S" category"?

To me it feels like a small step to add 'Use display title for sorting' and 'Use sort title for sorting'.