Oh, I think you might misunderstand what I'm comparing it to. The other tools, like Proverbot9001, are exactly the NNUE scenario you describe, where a small neural network guides a search procedure to find proofs; they are more effective at finding formal proofs than Llemma. For other tasks, like non-formal proof generation, Llemma has novel results as far as I know; it's just in terms of producing formal proofs that it currently seems to lack as compared to the state of the art.