Missing Crm 2011 german standard translations

We had/have a strange problem:
On newer OnPremise-installations (rollup 11) some of the crm-standard-labels (registers,...) were not translated to german and therefore displayed in english on the forms (e.g. "General" instead of "Allgemein"). We started then some study on the crm sql server database. It seems that CRM saves all the labels in her database table "MetadataSchema.LocalizedLabels" .
We discovered that on older installations the missing translations were saved under the solution "System" but on newer installations we didn't saw this translations. The newer installations were missing all labels with "LabelTypeCode" in {6,7, 8}.

So therefore we thought that this would be a crm-bug and wanted to open a support-case. But then after we accidentally created a further crm-organization on the same crm server the translations worked for the new created organization and after also miraculously for the older organization!
But also after this miracle we did'nt found this translations in  "MetadataSchema.LocalizedLabels".

Questions:
. Does anybody know how this standard  translations really work?
. Where are the crm standard translations for labels wit "LabelTypeCode" in {6,7, 8} saved?
. Is there a service which translates this labels (and was not running when the labels were missing) or are this labels hardcoded in code?

Thanks for your help

Karl