I can coroborate this in our case. But to be fair to OP, it requires having a very good onboarding process. We have weekly Clojure lessons where we teach the language, and good CR protocol so for a while all CRs go to people who know the language very well so they can give good advice about Clojure. And this works if you add new developers slowly, but can get challenging if you hire quickly. So I would say it still requires some extra effort and the motivation to do so.