It's not as hard as you think, he's an English speaker and French and English shares approximately 40% of the vocabulary. And once you have mastered French, you have the other 80% needed for Spanish as it's a Latin language like French.

How hard do you think I think it is? Are you implying that it's easy for an English speaker to master the English scrabble word list?

Well, I think it is impossible, so the comment works for me.

And I refuse to update my priors to account for the fact that somebody did it. Because I can’t even memorize the English scrabble dictionary well enough to enjoy playing. I am happier to live in a universe in which Scrabble is just impossible.

For the stated time frame, it's definitely as hard as you think, and then much, much, much harder.