I mean runtime guarantees and features. In this case: effortless / near-invisible concurrency and parallelism.
As mentioned, I did like Clojure. I'd switch to it if it was running inside the Erlang runtime (like Elixir does).
I can't endorse it because I've never used it, but: https://zread.ai/clojerl/clojerl/12-clojure-to-erlang-code-g...
To be clear, I'm not questioning your choice of runtime or language. I'm just curious why you think that "Programming language syntax scarcely matters", as to me that seems the same as saying "How a codebase is architectured and designed scarcely matters".