> even bad works tend to carry the exact same level of language

Maybe this is one of the better times to encourage "literate programming" all over again?

If the majority of the source is detailed prose comments instead of "code", you would be able to tell. I think you're correct that this is an information problem (like the law of small numbers).

I strongly believe that if a new project is interesting enough for someone to be reading the source of a literate codebase, the prose that goes with it will be distinct enough that the first publisher would necessarily have to be human.