I was thinking in the line of having one survey, that will be presented in French to the french speaking person and in German to the german one. Let's say the question at hand is "When is your birthday", the survey package should have the ability to say "Wann sind sie geboren" in German, if someone added the german language string to the question. The benefit is that you can have answers from people speaking different languages aggregated in one survey. But you answered already, that it is solely the UI that is i18n. Which is already a great step forward.