Fennel already "works". There's a small community of devs around it and in my opinion and practice, it remains a better choice to use instead of Lua directly. I don't even hesitate - whenever I need to tap into Lua-based engines, I would try to bootstrap Fennel on top - I use it with Hammerspoon, with Neovim, with mpv, and if I at some point I finally decide to switch to Wez terminal, I will for sure use Fennel.

That being said, Fennel is nice but ain't ideal, it's rather weird. It tries to imitate Clojure syntactically, without actually posing as a Clojure dialect. Fennel is extremely thin layer over Lua - you're essentially writing Lua with s-expressions. In Fennel, you constantly feel Lua's presence (1-indexed arrays, table semantics, nil behavior), while Clojure abstracts over Java/JS/Dart/etc., much more heavily with its own semantics. I constantly feel like I'm missing good CLJ ergonomics - no built-in immutable data structures; no rich standard library; limited REPL experience;

The difference in philosophy is that Fennel prioritizes being "just a syntax" for Lua and Clojure prioritizes being a "better language" that happens to run on JVM/JS/.NET/Dart/etc. Makes Fennel feel more like a transpiler - remember the days of Coffeescript?

I guess, maybe all that actually makes Fennel more appealing to some - abstraction layer thickness sometimes does matter. I personally, wish for an actual Clojure dialect on top of Lua, rather than something "like Clojure".