Given the existence of things like Occlumency, it seems that one wizard being able to read another's mind is not unknown. So some kind of magical Universal Translator shouldn't be a problem. So why, in Goblet of Fire, do the Beauxbatons and Durmstrang students have such difficulty communicating in English, and the Hogwarts students appear unable to understand any language other than English at all? (I think it's a given that there are no foreign language classes at Hogwarts; we certainly never hear of any.)
A skilled Legilimens may be able to understand somebody's intentions through Legilimency, but remember that this is an extremely advanced branch of magic. While Occlumency (that is, preventing your thoughts from being exposed) is easier and was practiced by both Harry and Draco at different points in the series, the act of extracting those thoughts was only possible by a select few very skilled wizards - Dumbledore, Voldemort and Snape primarily.
On top of this, we know from Hermione's analysis of some of the items for sale at Fred and George's joke shop that charming objects with special properties is also not easy to do. The implication is that the more difficult and powerful the spell, the harder it is to do. That would make an object that can perform Legilimency extremely expensive and rare, if it were even possible. And the fact that Dumbledore and Barty Crouch were known for being multilingual implies that this is not the case, or there would be no reason for them to learn a variety of languages in the first place.