While @mongoose_za's answer is comprehensive and helpful, it answers a different question, not a different one.
The real answer is simply to change the list of languages in the settings to include these own forms as such:
LANGUAGES = ( ('de', u'Deutsch'), ('en', u'English'), ('nl', u'Nederlands'), ('es', u'Español'), ('fr', u'français'), ('jp', u'日本語'), )
I added a couple to make it more obvious what we are doing.
Since you always want to display languages in your own way, there is no need to translate them, so there is no need for ugettext () wrappers. You want to make sure that the first line in your settings file:
So that everything is correctly interpreted by Python.
A great source for this exercise: http://en.wikipedia.org/wiki/List_of_ISO_639-1_codes
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