An easy way to keep up with changes in the original articles and to manage continuous contributions is to keep all translations in the translation project’s Sources repository. That way, it is easy to edit draft translations and install them in ‘www’ only when they’re ready. It is also convenient to update the translation (merge any changes from the original) while it is still under review.
See Team's Repository in The GNUnited Nations Manual, for more information.
Remember: A choice of a particular VCS is a sensitive matter—some modern ones provide compelling features, but they also bump the barrier for participation higher. The VCS is supposed to ease collaborative maintenance—if it eases only you, project members just won’t use it so that won’t be a net win.