I think you may have missed the point that the XKCD cartoon was making. The question here is NOT how to generate passwords that are hard for computers to guess. That's a solved problem: simply generate a 128-bit string with a secure random number generator, and that's your secure password that computers can't guess easily.
The PROBLEM is to generate a password where the ratio of ease-for-humans-to-remember to ease-for-computers-to-guess is maximized. Using words from a language other than your own is NOT a good way to maximize this. Introducing just one more randomly-generated word from your own language will be far more effective by this criterion.