C. figured the entire password out before me, but happened to give me a hint not on purpose: that the answer might have been in non-English, after all. It turned out to be kind of a mix? "Grattis" is "congratulations" or a short form for "happy birthday".
Two hundred and four (the chess board question)
Now, I have the best birthday gift for Silvia figured out, but for the summer. She was not happy at first, because she still was enjoying what was left of her current age, but I am quite sure my timing will be perfect :)