There is no correct answer to what languages IBM Watson currently supports. Each of the 28 services support different languages, services like AlchemyLanguage even supports different languages for each sub-api, sentiment (8) and language classification (97) as an example.
Today IBM took another step with Watson, this by launching a new division, the Watson IoT (Internet of Things). the Watson IoT Headquarters will be located in Munich, so finally some European spotlight within the Watson world.
IBM Watson is so much more the just a Watson assistant, but the interaction is done via a natural language interface, this so we can interact with Watson in the same way as we do as humans. This simplifies things tremendously.