In my opinion the world revolving IS the easiest "very hard" song, but it's not the easiest to full combo since it has a few actually hard sections, unlike megalovania which is decently hard throughout the whole song
idk i spent a day doing the world revolving and now i can do it consistently, and ive not sunk time into megalovania
well 6 minutes after i posted this... i beat megalovania
told you it's not that hard, I FC'd it first try when it first released