Please be more careful. You get some translations right on or at least very close, and others are just way the heck off. Danbooru policy is that no translation is better than a bad translation, since the latter spreads misinformation, but you obviously know enough to get some stuff just fine. Just double-check yourself, please.
@shirosuke86 Thank you for your feedback. I know 「お山の大将」is the equivalent of the children's game "King of the Mountain" or "King of the Hill." What's the negative meaning supposed to be? Is Cirno supposed to imply that the oni were acting childish, just playing a children's game rather than achieving anything worthwhile? If so, I've revised the translation a little to reflect that. Does it seem better now?
Ah yes, in a metaphor from the children's game お山の大将 can mean someone who brags about being the best in a small circle.
What does "Yama no shiten'nō" mean?The oni were the number one big shots on the mountain, by the way.Hey, you two!That's our Cirno!Really?That's crazy! That means that you two...!...there were four who were considered the strongest, and that's what they were called.Oh...Ah, that. A long time ago, among the oni who lived on Youkai Mountain...In other words, we big Four were like the controllers of the mountain....were playing King of the Mountain!?