first off, I am German and I have an IMO important suggestion to make for TESV. One little but severe thing that really drove me crazy when trying to use English mods in my German Oblivion, or later on vice versa with German mods in the English game, is an issue related to voice output. It's just a tiny thing to fix in a new game for the developer, but it would be frustrating if seen again.
The problem is that voice output files are searched in folders named by the name of the races instead of their editor ID. As such, while the editor ID of the races is identical in all different language versions of TESIV, the name of course is not. For example, as Argonian -> Argonian is the same in the English version, it is not in German: Argonian -> Argonier. As the voice output file folders are named by the name, the German one in that case is called 'Argonier' instead of 'Argonian'.
This might not be of any relevance when English users only use English mods (most likely), or if German users only use German mods. But as the German (or literally any other foreign-language) players try to use English mods, they have to bother with some annoying side effects of this difference.
First of all, this generally leads to the fact that all the voice output of mods of different languages is missing. As the lip files are missing, too, one can't even read subtitles. This must usually be fixed for every single foreign-language mod by renaming the race-named voice subfolders, so their name is in the necessary language. As it has to be done for every mod over and over again, it is extremely annoying.
The problem with these differences is even more severe when using race mods of different languages. As they change the race names back to their native language, the original voice subfolders are not longer recognized as belonging to these races. As a result, all races altered by such mods have no voice output anymore, not even the standard stuff. This has to be fixed by editing the .esp of the race mod with the CS and rename the race names back to what they are in the language version of the game. This still is some nasty work, as you sometimes don't expect a given mod to alter the races, and then you got no idea why the language output is broken.
And all these nasty problems - BTW the only technical problems when using a game and mod versions of different languages together, I dealt with that topic thoroughly - could easily be forestalled if in TESV, the voice subfolders would not be named (and searched for) by the (language-specific) names of the races, but by their ID. Or any other (maybe new) race-specific, language-independent value.
I hope this point will be perceived.
Sincere regards.