Hi Veysel,
for adding a new language to an EBS 12.2 system.
1.License the additional language.
2.Maintain the multilingual tables.
3.Update the snapshot information for the complete APPL_TOP.
4.Create a translation patch synchronization request. (applying a translation sych patch is recommended)
5.Apply the translation synchronization patch.
6.Generate message files.
There may be some specific problems after adding a language.
but, your issue is not acceptable.
Navigation menu - Home page still in English?
Weird.
Take a look at this blog post ->
http://ermanarslan.blogspot.com.tr/2013/05/investigating-ebs-nls-data-load-problems.html