Interesting, but the criteria of "fluency" in such kind of sport are questionable. He may feel himself "fluent" in a language but I doubt that such "fluency" will help native speakers understand him or vice versa in practical situations. He means a very primitive level of language understanding. On higher levels difficulty is caused by other features. Even the practical vocabulary is much more essential problem IMHO.
P.S. Spanish is easy. No, really.
"I must give it to him." = "Tengo que darselo." Google translate fails.![]()