Where did you find that stupid list? 8notes.com? It seems to be written by someone with truly limited knowledge of playing piano Rondo a Mazur is easier than a Mazurka? BTW, Difficulty is extremely subjective when it comes to Mazurkas There's like 52 of them
OK, oops! Wow! That's some task to work on that listing. Obviously there are going to be some weirdness to the list. However, if it was 8notes.com, I'd never forgive them (OK, I would, but still. It's a figure of speech )P.S. Sorry!