Help for Region & Language settings besides Language

[rsbrux]

The handbook for KDE Region & Language settings has only one page (about 
Language) in German.

As a native English speaker, I installed Ubuntu Studio 24.04.1 LTS in 
American English, but I would like to have access to other regional 
settings.  Despite having added French, German, Italian and Spanish 
under languages, I still see only English-language locales for the other 
options under Region & Language.