This paper reads like a long-form-shitpost of the highest quality. Both made me laugh and taught me something interesting. Of course, which language another uses to explain that something sounds like gibberish does not tell you anything about which is harder. And, judging by their flimsy yet insistent and very eloquent justification of their methodology, the authors were well aware of that.
It is very cool to see Chinese coming out on top. As for the Norwegian that they left blank, I'll be happy to add that we use Greek to express that something is unintelligible:
Det er helt Gresk for meg.