QT 5 UI language and local settings

I'm on Kubuntu 19.10 I have set Regional Settings > Language > British English (Configure Plasma translation)

but as I'm living in another country I must set Regional Settings > Formats > Other Country - other_LANGUAGE

Everything is fine with KDE and GTK applications (i.e. English UI and local calendar) but QT applications show the other_LANGUAGE in their menus and toolbars.

Is there a way I can fix it? I've been "duckducking" for hours but no luck.

TIA

Know someone who can answer? Share a link to this question via email, Twitter, or Facebook.