This article has not been completed yet. However, it may already contain helpful information and therefore it has been published at this stage.

Introduction:

Set-WinUserLanguageList -LanguageList DE-DE

After the installation has been completed, you can then use

Set-WinUserLanguageList -LanguageList DE-AT

to restore it to its original state.

Conclusion:

Sources:

SQL Server does not support the language of the OS