How can I use a custom locale throughout all KDE apps

Hi, I recently made my own custom locale for my system by the name of “en_US_x-dio”. The main difference between this locale and regular “en_US” is the date and time formats. In my console, it works great when set as LC_TIME, but I can’t seem to get the language to apply in any KDE apps, including Plasma desktop. My custom locale simply does not appear in the “Region & Language” pane. When clicking the “Help” button in that pane, I’m taken to a help article for KDE5 despite being on KDE6. Does anyone know how to get my custom locale working?

KDE uses the Qt locale system, which uses the Unicode CLDR database through the ICU library. ICU does not - to the best of my knowledge - allow user locale customizations.

That’s rather unfortunate to hear. I really do like using KDE apps and the Plasma desktop, but if I can’t apply my custom locale then I might honestly have to consider switching to a different DE.

If your custom locale is just copying time presentation from a non-en_US locale, then Plasma does allow you to choose a different locale for time than for anything else.

If it is a fully custom thing that does not map to any existing locale specification - then I’m sorry but this is how it currently works.

It unfortunately is fully custom, the closest one I found to mine is en_SE