Toolboxes locale

As said in an other post, I’m french, and trying to use toolboxes to launch GUI app which I can’t find among flatpaks (this to avoid overlaying excessively with rpm-ostree), and I can’t prevent GUI app’s menu to be in english, and not in french. I tried to set the locale in /etc/locale.conf inside the toolbox, and then to reinstall the app (vlc, grisbi), but I encountered this error message: “(grisbi:116722): Gtk-WARNING **: 12:30:37.431: Locale not supported by C library. Using the fallback ‘C’ locale.” ; and in fact, reinstalling vlc, I can read this brief message just after launching the install : “Failed to set locale, defaulting to C.UTF-8”.
Is it a normal behaviour ? How should I set the locale in a toolbox ?
Thanks for advices.

After searching more and better, I installed glibc-langpack-fr and exported LC_ALL as fr_FR.UTF-8… without any success… only the error messages disappeared.

Does installing sudo dnf install langpacks-fr.noarch in toolbx help in any way ?

I’m able to replicate this “the other way around”

On host when I run LANGUAGE=fr_FR nautilus it brings nautilus in french. That doesnt work from toolbx. It’s probably worth creating new issue on GitHub - containers/toolbox: Tool for containerized command line environments on Linux
It’s probably missing some package.

Thank you for your message.
I tried your propositions, but it changed nothing.
I’ll create the issue on github.

Issue #967 created on github, hope it’ll help.