If you are using 2.3.0 the language files are standard encoded in UTF-8
The danish language files for 2.3.0 is not at www.xoops.dk
The only online language files is for 2.3.0 Beta, and they are encoded in ANSI (Latin1)
So, unless You have translated them youselv ore change the encoding til UTF I think You have the wrong language files.
It works with HTML for special characters, but it's not the solution. Every time you download a new translation, you have to chance it to HTML
At the moment xoops.dk and xoops.no is moving all activity to xoopsnordic.org
We will have a bigger community there.
The first thing is to get the forum and download-section up running.
Then all files will be encoded in UTF