The first time Zoro hold Enma, he managed to get his ryuo back after Enma absorbed it up.
He most likely used CoC unconsciously, but since then, he still has struggle to tame it perfectly. It's probably because he doesn't know how to fully harness his CoC yet.
It seems that Adv CoC is related to Ryuo as, just like Adv CoA, you need to let your haki flow out of your body to coat yourself with it.
So after Zoro wakes up, he will learn how to incorporate Adv CoC into his blades in order to subdue Enma for good.
He most likely used CoC unconsciously, but since then, he still has struggle to tame it perfectly. It's probably because he doesn't know how to fully harness his CoC yet.
It seems that Adv CoC is related to Ryuo as, just like Adv CoA, you need to let your haki flow out of your body to coat yourself with it.
So after Zoro wakes up, he will learn how to incorporate Adv CoC into his blades in order to subdue Enma for good.