{Counterspell} is imprinted with {Isochron Scepter}. my opponent has {Curse of Echos}. Can he counter my counter that is imprinted? Meaning, I use the ability on the scepter to counter something and he chooses to copy the imprint and counter it.
Yes. As the copy the scpeter makes is still cast, each other player will get a copy of your copied spell.