Can a Returned be made from Stormlight?
How would you count the Heralds?
I haven't read much, so I don't really know what you're talking about.
In the Stormlight books, there is a set of people who are constantly reborn, into full sized grown bodies that are being created for them. Would you count that as being Returned?
Or do you count Returned...What's your definition, right? You can create something that is Returned-like. But your definition of what is Returned and what is not, is going to be involved in that.