Well, lets blame Redmond, or why not ... lets all drive on the right side of the road.
No, seriously, sorry for being testy about it. The site is installed on a Swedish server, that had swedish nationale. But changing this didn't alter the presentations. Neither did changing the database collation settings. So somewhere deep inside the throat of .NET or SQL-Server, or even within the registry this setting grins us in the face. Also the guys at CS / Telligent haven't responded - so probably they haven't tested their product in international waters... as fine as it is.
The next version of this community will be in CS2007 and that one will be installed on an English locale server, I promise. 
Kind regards / Peter