They don't report the pass@1 success rate. They sample multiple solutions from Opus/Fable and CLM decides which one to submit, that's why they get >80%.
Maybe I'm misunderstanding this but when would you ever use it this way? If you're already willing to call Opus/Fable, then isn't the obvious comparison whether Opus/Fable can choose among sampled solutions better or worse than their fast model? If you're willing to pay many seconds for many code samples from a slow model, it's contrived to imagine you care about picking between them in ms.