I suppose that leveraging the two existing languages can help reduce ambiguity and improve the translation to a 3rd language?
Example: - the menu has "Home" as a first item, in English - in French, this item is translated as "Accueil" (literally, 'welcome' in English) => together, these point to a precise meaning of the item, that should be close to "Startseite" in German, not the German term for "Home" nor "Welcome".
Do you know of any translation service that would offer this feature?