More headcannon.
Here it is again.
The manga explain to us how enma works. Anything more is BS. The manga has never stated or shown enma affecting Zoro's other swords.
This is Zoro when he doesn't have control of enma.
Take notice that even though Zoro is not in control of enma it is not affecting his other swords..
This is Zoro when he has control of enma and Zoro is releasing and coating all swords with an incredible high amount of CoA haki.
Take notice there is no black lightning at first. He doesn't add it until his starts his attack.
That aura or smoke is green when Zoro is in control.
Purple smoke when he loses control.
This is Zoro using ACoC on the demon splitter only.
Take notice there is no green aura which tells us that is a separate power than ACoC.
I didn't assume anything. Flowing haki is flowing haki. Zoro can apply it to CoA and CoC. That's how Luffy learned it.