The funny thing about your post is you haven't even proven whether the lightning that Luffy used against Kizaru was CoA. You just assumed that is CoA.
You need to go back and read the scene about Zoro mastering enma because you don't even understand what the scene was about.
The scene was about Zoro realizing the way to master enma was to release and coat enma with overwhelming haki (all the haki he could release) even if it kills him.
When he did he subconsciously released and coated his sword with CoC that was shown as lightning. We have never seen his swords coated with lightning before and fodder lost consciousness from the lightning. Both of those scenes tells us Zoro coated his swords with CoC.
From that point on whatever we see lightning it means his swords are coated with CoC.
Yes, is that easy and simple to understand.