"Please come down" should be accepted. "~세요" implies politeness, so there is an implicit "please" in here. We use "~세요" in polite, honorific situations... that important piece of context should be in the English translation. Please flag this to add the alternative answer with "please".
Get down, come down, go down, are all acceptable translations of this phrase. Korean is not that specific. Fred and other great contributors do not have the time to look up all the possibilities in English. They need to add these other options when they get a chance. Thanks to Ash-Fred and all the other contributors to the Korean section of duo lingo
"Please get down!" is now accepted. "Please go down!" would be "내려가세요!"
Please come down. reported again 1/10/18. I expect the developer thinks the exclamation point removes the need for "please." However, the fact that it is an order doesn't prelude the person in authority from saying "please", so please 이란 안 받는 것은 좁은 생각입니다.
"Please come down!" is now accepted. We simply omitted this translation; this has nothing to do with the exclamation mark. I am not quite sure what you want to say with the Korean, could you write it in English?