by Marius Jugariu.
The swedish language pack seems to have been updated yesterday - http://download.moodle.org/download.php/langpack/2.5/sv.zip and has only 82% of it translated.
If you go to http://yoursite.com/admin/tool/customlang/index.php (replace "yoursite.com" with your actual site) and select the swedish pack, you can then "open language pack for editing"
After it loads up you can either select to show the strings from "mod" of assign.php or search for strings related to assignment and modify them accordingly.