Have a friend who works in superconductivity and from what they say this is pretty standard - the way experimental superconductors are generally created is by spraying atoms onto a film over and over until you get one that works [< 10% success rate is common]. There are other ways to do it more reliably and in larger quantities once you have a confirmed superconductor, but they're also slower during the experimental stage.

I was a chemistry major, but didn’t take it up as a career so I won’t pretend to be an expert. There are a lot of tools in the chemist’s cookbook for dealing with exactly this sort of problem. It doesn’t mean it’s easy, but experienced chemists will understand how to approach solving this.

I'm guessing the diamagnetic property will make it easy to separate the successful bits from the unsuccessful ones at scale.