Can the PIM Docker image support multiple languages?

[Glen Ditchfield]

I use the PIM Docker image for development , and I'd like to inspect the UI in 
non-English languages — in particular, Akonadi's Calendar Properties dialogs.  
Is there some way to add languages to the environment?

System Settings, Regional Settings > Language says “There are no additional 
languages available on this system”, and only offers American English.    
Setting LANG on the command line translates some items — some button labels, 
month names ... — but not menus and such.