The roads I take...

Since Firefox landed on the L10n CVS, German localizations for Mozilla core strings have been done separately in two places: On one hand, there was my private MozillaTranslator repository holding the suite localization and maintained by myself only, seeing fixes through occasional bug reports. On the other hand, there was the L10n CVS version used for Firefox and later Thunderbird, which originally based on my work, but diverted as Firefox localizer Abdulkadir Topal maintained it, adding his own sets of changes, probably coordinated in different cases with Alex Ihrig, who is the Thunderbird maintainer and German core L10n peer.

Now that we are working on finally getting suite L10n into CVS as well, I could just concentrate on SeaMonkey-specific strings and just adopt what is in CVS for the rest - but there are two problems with that approach:
First, due to changes on trunk and Abdulkadir having little time, we lack some translations for core in German CVS, and I'm happy to help out there a bit (some people might remember my fight with nsserrors.properties a while back, which was an instance of that).
Second, it's a good idea to review where translations diverged between my version and the one in CVS, as either version could have better solutions for some hard cases and some systematic differences may be worth a discussion that makes us consistently improve our work across core and the different applications.

Because of that, I filed a set of bugs about syncing up our different versions, and both MozillaTranslator's "Search Translation Inconsistency" and my PHP script to rewrite output of that tool with the structure of the original files did once again show their usefulness.

Sure, the result was a few huge patches (and I haven't even touched toolkit/ yet), which take my colleagues some time to review, but I'm convinced the result will be a better quality localization for all German users, and that's surely worth the time we all are putting into that.

And we even came across a few things which are bugs in the original strings and which German localizers have solved silently in the translation only, but they really should be filed as common bugs, so we can improve the product for all our users. This includes the security libraries of Thunderbird and Sunbird not talking to the user as if those applications were browsers, Firefox telling the user it stores email passwords or just resolving our mixed use of "website" and "site" across the core strings. We'll sort those out, file bugs where necessary and care that the situation gets better for all of us.

I also want to ask localizers of other languages to do the same: If strings in the en-US original are strange, wrong or inconsistent, please don't hesitate to file bugs against the original code.

Better quality for everyone is surely worth investing some of our time, we all should our share to ensure it's possible.

Edit (June 22, 6:30pm CEST):
Some bugs we spotted in the original strings are filed now - and we may find even more