Ah. Sorry I just realised we have different language tools installed. I am using the paid version of WPML (not qTranslate) and when I use %%extract%% (for example) for the meta description, the language changes like it should.
We’re using qTranslate and it seems possible to use short tags to use different titles and descriptions for different languages. This works for us:
[:en]English Title [:se]Svensk titel
qTranslate then picks the correct title and description based on the language used in the frontend by the visitor.