Not able to have themes applied

I am using Gentoo with KDE/Plasma under WSL 2.

I can select themes using systemsettings, and the configuration is saved, but the themes are not applied. I’d like to debug this, but I have not idea where to start…

In the meantime, I managed to apply the theme to most apps using qt5ct.

That will break most of those apps; I don’t recommend using qt5ct.

I’m afraid I can’t help you troubleshoot the original issue as it seems like you’re doing something very novel and creative far outside the expectations of the original developers, and are squarely in “there be dragons” territory. But hopefully someone else here can help you!