At present $swapprefix() only handles English prefixes "A", "An" and "The", and if you want to handle other languages, then you need to explicitly specify the list of prefixes you want it to handle.

I would like to propose the following enhancement to $swapprefix:

1. If the list of prefixes is explicitly provided, work as-is.
2. If the list of prefixes is NOT explicitly provided, then (if it exists) use MusicBrainz language data to add a pre-defined language-specific list of prefixes to the English list: A) If the track work language %language% is specified (and not English), add that as well; B) If the album language %_releaselanguage% is specified (and not English), add that as well.
3. Potentially provide a further parameter (or if necessary a new $swapprefix_langs() function) which provides similar functionality using the combined list of all defined languages or if a parameter is specified, a defined list of languages.

This should largely be backwards compatible with existing usage, but will avoid the need for the user to research and add new explicit prefixes to their scripts every time they have an album or track in a new language.