I wonder if the Page Translation[1] feature of the Translate
extension[2] would make it easier to manage this, It appears to (but
not written), that when the main translation (en for example) is
"touched" that it will mark the other ones for needing updates.
[1].
http://translatewiki.net/wiki/Translating:Page_translation_feature
[2].
http://mediawiki.org/wiki/Extension:Translate