Activating admin_language site-wide makes site unusable

I'm running a kurdish website, with english and arabic installed as well. As some editors can only work in English, it is crucial that they are able to navigate the site as such. However: admin language configured to english works only when you only activate it on admin/* and node/* pages. If it is activated on front-end pages (so public content), it seems it thinks it needs to fetch english content (of which there is none atm). So what happens when I configure AL (with english) on front-end pages? It translates everything in English and seems to retreive english content, even though you are on the kurdish section. Meaning: AL can only be configured to be activated on administrative pages. And that is workable. However, I'd like to have an English menu, no matter on which page I am.

Is this a feature? Or is this a bug that needs to be solved?