Hmm could some developer take a look at this old topic and the ticket associated with it:
http://trac.xbmc.org/ticket/4437
I've been trying to use XBMC as a PVR frontend for my VDR based HTPC (currently using XVDR plugins for this) for years now. But I've always had to turn it down due to the subtitles and audio track problems that would simply go away if I just could set a separate language selections for a) XBMC UI language b) audio track language c) subtitles language. Currently it's just a mess.
My native language is Finnish, but I can't stand using anything else but English as the interface language for computers. Local translations always suck so hard. So I want to use XBMC in English. This causes problems when viewing live TV. I'd like to use Finnish audio and subtitles and fall back to English if unavailable. For foreign material many Finnish TV channels broadcast an audio track for people with poor sight which is basically the Finnish subtitles spoken aloud by computer. This track is coded as being Dutch. Let's say the original programme is from Germany so the original audio track is coded as German. Now when viewing a program like this, very often the "Dutch" track is selected instead of the original German track. But I would of course prefer the original German track with the Finnish subtitles. Another problem is with the subtitles. Some channels broadcast multiple subtitles, e.g. Finnish, Swedish, Danish and Norwegian. Most of the cases something else than Finnish subtitle is displayed by default. And the best or worst part is that you never know what you're going to get.
In commercial set-top boxes it's a standard feature that you can configure the interface language and set language priorities independently for both audio track and subtitles. I would really love to see similar functionality in XBMC. And this selection would of course be generic for XBMC, not just for live TV, so that the priority lists of languages for audio and subtitles would be taken into account when choosing DVD audio track/subtitles or external subtitles when playing movie files.
Someone mentioned setting the audio and subtitles manually. Sorry it really isn't an option if you're channel surfing and you have to pop up the audio menu 100 times in a night. Way too annoying, the correct settings need to be applied automatically each time you switch the channel.
Magic is good when figuring out defaults, as long as the bad defaults can be overridden. If the XBMC developers fear that implementing a feature like this would clutter the interface, I would be happy if the functionality would be available in the core XBMC and configurable by manually editing the XML config files under your ~/.xbmc, no UI needed.