This might be a little far out for an Mp3 tagger program but give it a chance. I have thousands of files to clean up and rename on occasion. Mp3tag has the best scripting of any file renamer I have found. Some look pretty but just don't work. Others have a few locked in choices that may or may not work. Would it be possible to have a stripped down version of Mp3tag that can format and edit any type of file. Or make it so that Mp3tag could turn off the mp3 tag section of it and just work on filenames of any type. I have tried doing file renaming with it by adding an mp3 extension to my files and then removing them when I am done. Even with the hassle of doing that and Mp3tag looking for non existent tags I got a good feel from it when handling rtf, pdf, ect with it. It is just the Mp3tag is such a pleasure to work with I would like to extend what I can do with it. If this can't be done I will continue to look for a better file renamer that comes closer to your standard.
Yeah, probably a little far out there.
My suggestion would be to learn a scripting language that can run on your system - Python or Perl are a couple of good choices that you'll probably soon find to be far more powerful than the scripting capabilities of Mp3tag.