tinymce/jscripts/tiny_mce/langs/readme.txt

Beginning with version 2.0.5 the language packs are no

Beginning with version 2.0.5 the language packs are no
longer included with the core distribution.
Language packs can be downloaded from the TinyMCE website:
http://tinymce.moxiecode.com/download.php

The language pack codes are based on ISO-639-1:
http://www.loc.gov/standards/iso639-2/englangn.html

Plrease try using entities if possible. Like å etc for non a-z characters.