I am against the notion of a German help-center
There is a few reasons for that, so here's the TL;DR; up front:
- It's bound to be out of sync with the original.
- It is not accessible from the help-center.
- It facilitates a "two-culture-split" (English vs. German)
- It opens the door to German discussions on meta.
- It's a challenge to the help-center as single source of truth.
It's bound to be out of sync with the original
This one is somewhat simple to explain. Translating always is associated with interpretation. Accordingly two translations of the same text seldom (or maybe even never) overlap fully.
Additionally this "second help center" has to be maintained. With every change coming from our meta, as well as parent meta, that has to be translated and updated.
This is a problem because help-center changes don't come with a notification. Somebody has to watch these changes, notify people to translate it (or translate it themselves) and then edit it into some huge post-collection...
That's already a huge effort.
It's not accessible from the help-center
This is one of the biggest flaws of this. I cannot link people to two help-centers at once. Also editing the help-center pages to link to the respective German posts is inefficient.
Those that read the English help-center don't need the German help-center and those that need the German help-center don't read the English one.
It facilitates a "two-culture-split"
We already have a problem to bring the two cultures together. I often see discussions about important site-business happening in German. While I personally don't have much of a problem with it, it excludes users that don't (yet) speak German well enough to contribute.
It also excludes a lot of the StackExchange employees responsible for community management.
Overall it's a subversion of English as the "lingua franca of site-business".
Additionally it's a huge exclusion factor for users who speak English better than German.
Adding this help-center clone would furthen that already happening split between the German community and the English community. This is something I'd like to avoid, because this site cannot harbor two distinct communities by design.
It opens the door to German discussions on meta
I think it's fairly self-explanatory. The reasons why I consider this a bad thing have been made clear. It shouldn't happen that a language that's accepted as the means of talking about site-problems and General "business" in the WHOLE SE NETWORK becomes an "option".
There needs to be a common denominator for the community to allow for a place to communicate and build the future of the site.
That common denominator cannot be German, not in a network of english-speaking sites.
It's a challenge to the help-center as a single source of truth
This is where the real problems start. I already can see the debates about nuances happening, about "but the German help-center says ...".
The sole existence of an alternative to the single source of truth is a threat to the community. It opens space for cherry-picking the "right rules".
This opens up wide for confusion in regular users, close-voters and "externals".
The single source of truth is the strongest point of StackExchange sites, there is no debate where the rules are, or who makes them. Everybody knows what's up for discussion.
This changes drastically when the single truth is compromised.
Overall I think there's too many good reasons against such a German help-center to create one, no matter how many good reasons for such a help-center may be there.