Problem with MinimServer language setting on Synology NAS

[steamfan]

Hi,

this was very helpfull to get the German labels on my MinimServer instance which runs directly on my Synology NAS.
i have additional instances running as docker containers. How do I get the German labels there? I tried to exchange in the environment settings LANG "en_US.UTF-8" by "de_DE.UTF-8" but this had no effect (process: container stopped - settings changed and saved - container startet). What am I doing wrong? And would this also allow special characters (German, Swedish, French, etc. special characters)?

Regards