I believe "Prototype" is a prefix found on world drop boes

Expert is surge rating

I only knew the one recipe and it was the very next Re of the prototype after I had learned the Artifact Item in question was Prototype- Overkill Durable Combat Jacket Artifact-Expert Durable Combat Jacket(Superior)

Not sure if its common knowledge but it seems you can "learn" the same recipe multiple times and it will just give you an error message. Kinda sucks since there is the same chance to learn a single recipe every time regardless if you learned the others. Hopefully its just a bug *Occured for me on the blue to artifact*