Dear team,
We have 1 site for each language/target audience. We observed that if a language (e.g. 
German) is not available on the site (Site Settings > Localization), then even if our editors’ user profile (Account Settings > General > Personal Information > Language) has the language, they can only view the site in the one target language (e.g. 
Czech).
This does not make much sense because a company may have German editors who also work on content for Czech without having to know the target language.
So it would be best if the user account settings would override the language for the backend features.
Having both language active is not an optimal solution because it leaves the option for the editors to create German translation, even if the company does not want them to do that.
A better solution would be having an Instance Setting to control if the portal’s displayed language should be based on the user profile or the default site language.
I hope you’ll consider our request.