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Mazarin: No - I don't think there is a complete list - but there is a need.
The normal folders
\ language
\ module \ system \ language
\ install \ language
\ module \ modulename \ language
is a good place to start, but You will not get the themes and editors translated - You can try to download the danish tranlation of 2.3.3 - I have done some translations for the editors, too.
Remember to use UTF-8 encoding.
You don't need to start all over, You can edit the existing translations.
Do it local and use Wishcrafts Xtran module.
(Sorry for late respons on xoopsnordic, but ordenary work is taking to mutch of my time theese days)