a.l.e, I think daniel knows to use styles to format text, since the question being asked - as I read it - was whether there was a way to organise styles within a document, not about how to organise documents.
daniel, at the moment - in 1.4.6 at least - there's no in-built way to organise styles. They come in the order that Scribus puts them - alphabetically - and there's no way to override that without naming them in a specific way, as you are already doing.
Just out of interest, how many styles do you have in your documents? For most documents it's usual not to have more than a dozen paragraph styles and maybe the same amount of character styles (possibly a few more). I'm not saying that you're doing anything wrong - you can have as many styles as you want - I'm just curious as to why you need so many is all.