I do not know how user "Invictus" would like a batch renaming function to work, but here are my thoughts of how I would like such a function to operate:
1) It needs to be similar to the "Tools, Tagging Tools, Renumber Tracks" function.
2) The same "file renaming template" provided by the "Rename" command when editing tags must be available.
3) A warning, perhaps within the displayed "original filename / new filename" list, must be provided if duplicate filenames within the same folder are generated, or if filenames (including extension) longer than the maximum supported by the disk OS File System.
4)
That's about it, really.
As far as the renaming templates go, you can modify them as follows:
1) When "<Artist>" is used, and the track has more than one artist listed, the generated output currently does this "Artist 1,Artist 2,Artist 3". The output should rather be padded with spaces to become "Artist 1, Artist 2, Artist 3"
2) Perhaps add a new renaming field so that instead of using all artists like <Artist> currently does, only the first specified track artist is used.
And while not explicitly connected to this topic, I'd also like to see ALL available MusicBee commands and functions be hot-key assignable. For example, the "Tools, Tagging Tools, Renumber Tracks" command can currently not be assigned a hot-key, along with many other commands. And along with hotkeys, perhaps a customizable global toolbar that appears under the main window title bar.