Language support seems not to work as it used to

As I recall it used to be that you could turn any version of Project into a foreign one by downloading the language.  I have done this before for example for French, German, and Brazilian Portuguese, I think using project 2010 and Windows 7. 

I am now trying to do it for Swedish, using Windows 8.  I have tried both 2010 and 2013 and in both cases Swedish shows up on the File/Options/Language dialog but:

1. I see no way to select it other than by making it the default.
2. If I do that it affects the whole system (e.g. Control Panel) not just Office.
3. And it still does not do what I actually want, namely to translate things like the strings used to specify duration units (e.g. “weeks” in English, etc.).
   

The problem is not the fact that it is Swedish, btw, because I have tried the other languages mentioned above.

 Any ideas?  Have I forgotten to do something?