Office for Mac buy from Sweden
This is not a problem. What matters is the serial.

The same serial should work with any language version of Office Mac 2011 which you can download from Microsoft's official websites.

I had a similar problem like you. I had purchased an English version via Ebay,  but I needed a German one. I downloaded the German version and used it with and US version serial without any problems. 

In your case you can download the US version here: www.microsoft.com/mac/downloads