Changing the application language shouldn’t change colour theme
Not sure if this is an KDE issue or Kdenlive.
I am sometimes switching between different application languages via Help > Switch Application Language… I am using the "breeze dark" theme. Now when switching to an other language (e.g. from German to English) and restarting kdenlive, the application uses the (light) "standard" theme. Switching back to the old language (German) without any changes on the theme, the "breeze dark" theme is used again. But if I change the theme on the new language (English) to "breeze dark" and switch the language back to the old one (German), now the "standard" theme is used on the old language. And switching back to English again the dark one is used.
Tested using Appimage 20.04.2c on Ubuntu Studio 20.04