Am Mittwoch, 12. September 2018 schrieb Stefan Krusche:
> Getting closer... :-)
>
> $ tdecmshell language
>
> starts the mentioned TCC dialog directly. I'll investigate further and
> report what I find.

tdecmshell also offers a "--lang <language>" option to "Specify a particular 
language". I haven't found more information, the man page is scarce and says 
nothing about how to specify or format "<language>". So I tried with commonly 
used strings. However, instead of what I would have expected, neither of the 
following starts the language settings dialog differently from what is 
configured globally:

  $ tdecmshell --lang en language
  $ tdecmshell --lang en_EN language
  $ tdecmshell --lang C
  $ tdecmshell --lang C language
  $ tdecmshell --lang en_US language
  $ tdecmshell --lang en_US.UTF8 language
  $ tdecmshell language --lang en_US.UTF8
  $ tdecmshell language --lang en_US
  $ tdecmshell language --lang C

The command "kcmshell somemodule --lang en_US" is found a few times on the web.

Do I understand correctly that

1.) option "--lang en_US" should start a control center module with US American
    English language interface (like the menus, items, drop down lists etc. in
    English) ?!

2.) "en_US" or "C" is the default integrated language of the default
    installation of TDE without additional language packages?
    I have tde-i18n-de-trinity installed as the only additional language
    package. Accordingly I get offered "US English" and "German" in TCC language
    modul -> "Add Language"

If 1.) and 2.) applies then "tdmshell ... --lang ..." doesn't seem to work on my 
system. I would like to know because if it would that would exactly match what 
I originally was looking for -- at least for this one program, tcmshell.

Any hint is appreciated.

Kind regards,
Stefan