A new feature should be added. It should be possible to use a sort of routing mechanism for non-translated messageid's.

If a messageid is not translated in a particular language it should automatically look for another defined language... So you should be possible to do something like this:

Translate Spain: String 1 not translated in spain -> goto French -> String 1 not translated in French -> goto German -> String 1 not translated in german -> return messageid

a new "setDefault" method should be able to define such fallback rules. So strings which are not translatable in one language will be returned in another language.