After a certain point, I'm plotting to clarify and summarize this spell as clearly as I can in-comic, because confusion is still happening. I want to do as much "show" before I leap into "tell", but there comes a time in stories with weirdly unusual and technical abilities like this when you just gotta throw your hands up in the air and show all your cards on the table, because a good portion of the audience is just going to be confused if you don't.
That said, I think it's pretty simple once one gets it, but aren't a lot of things like that? Heck, making it so Carol's hair could be changed separately from the rest of her in a copy/paste scenario is simple, but I still gave myself a headache sorting it out the first time through.
Granted, I am a poor judge of what's easy to understand when it comes to stuff like this. I grew up watching Star Trek: The Next Generation, The X-Files, various nerdy cartoon shows, and hung out in a comic shop in which such things were hotly debated. As a result, this sort of weirdness is second nature to me.