So adding translations to the articles has been going pretty well! However, I think I've reached the extent of what Google can scrounge up for me in finding official card names. It's time to call in some native speakers. Here's what we still need:
Dutch: Seaside, Prosperity, Cornucopia, Dark Ages, Promo
Italian: Pretty much everything (working on this myself, but the cardlist I found is just a list, and does not have the official cards, so if I put up a wrong translation, and you have the set in Italian, please fix it!)
Spanish: A couple promo cards
Finnish: Everything (Awaclus? Eevee? Think I saw someone else Finning around)
Swedish: Everything
Chinese: Everything (please include transliterations)
Greek: Everything
Hungarian: Everything
Japanese: Everything (please include transliterations)
Korean: Everything (please include transliterations)
Norwegian: Everything
Polish: Everything
Portuguese: Everything
Romanian: Everything
Obviously, not all sets have been released in every language (Russian has only been released in Base and Intrigue), so just do as much as you can. And please add a literal translation if it's not a direct translation.