For language translation, you would need an external library or an external API (Google, Bing...).
To make API calls from a visual preparation recipe, as of today, the only way is via the custom Python formula processor. But, I wouldn't recommend that as it would slow down the UI, making a lot of API calls as it refreshes at each modification.
The best way is probably via a Python recipe (and not in a visual recipe). Also, I would recommend caching somehow the results to save some calls.