1. i didn't say the size of the mountains Sensui could bust with his fist. Sensui's fighting style specializes in kicks, so it's more like 4x to 6x in his case as well.
2. The auras went way up into the atmosphere, making then up to small county level.
3. YYH uses power levels and auras. Showing off their auras is a display of how powerful they are, they even kind of state this a few times. Guy did the same thing when he unlocked his gates.
4. If you don't believe in simple power scaling that's on you. Almost every verse has power scaling including Naruto with guys like Juubito being considered small county level based off the Juubi's Multi Mountain feat.