I am a long time pirate and i love to download media. (movies and tv series and other media) A problem that i have with the current releases by the scene is that there are only in English. (i don't count Anime)
This is the last view years come better with the movies and series that come from Netflix but there are a large gap with subs but i like to have my cartoons and if possible anime in my local language with Dubbing.
I like to see that the groups in the scene start provide the alternate dubs, I don't mind if this happen on scene releases day of some days later.
This can be include in one mkv file or individual audio files that can easy include in the mkv files.
This is not mean that there are some problems with the size if all the dub track are include.
An solution for this problem is if we can crate of extent a media container that can over write audio channels. May there are more problems but i think this is a matter of time for fixing this.
edit: In the context of my post i speaking about the lack of multiple audio tracks, where subtitles are in a better situation.
A special for archiving media for the future.
You can find subtitles online separately, because the subtitles aren't really cracked down on by copyright enforcement (since it's only text files that you need to have already found the movie to use).
I like your idea of something like an audio track, but only for dialogue/audio that was changed in the translation. This doesn't really exist, but it'd be cool if it did, especially for stuff like The Simpsons where jokes change to make more sense to different audiences.