Currently, I think there is no easy way to translate the extensions of MediaWiki into other languages. I suggest to create a hook, or something like that, in the end of every messages list in every languages (named "addMessages", "addMessagesDe", etc.), and to add their returned value to the array. The extensions will add functions like "MakeSysopMessages", "MakeSysopMessagesDe", etc., to these hooks. Is it possible?

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#define Name RotemLiss
#define Mail mailSTRUDELrotemlissDOTcom
#define Site www.rotemliss.com