Well since you asked for a PEACH.

It's attack bonus is higher than indicated (should be +22 BAB +8 Str -2 Size for a +28 total), and it needs a listed damage on its acid breath weapon. Also is Hilarious Presence a mind-affecting effect?

Other than that... I'm not the best on CRs but I don't think it's as powerful as a pit fiend. A pit fiend has 50 less hit points but a better DR, 12 more AC (which likely means 5-10 points of PA rather quickly), the hilarious presence and comedy spray are something, as is the Grease effect, with comedy spray being a 50/50 chance of being an AoE turn denial effect IF they fail the save. As for its saves only its Fort save is up to CR 20 standards. It also lacks meaningful immunities to cover this weakness.

Not saying any of the above need to be changed, but I might reconsider the CR down to 18 or 19.