I've been writing my Minetest Cereal project using Racket. That worked great for:
Unfortunately, the Minetest world format compresses some of its data using zlib. Zlib is not available in Racket at the moment. I tried working with the gzib library instead, since they use the same core algorithm, but it wasn't as compatible as I needed it to be.
Short term, I'm rewriting what I've got in Python, since it's known to work. I hope I'll also get a chance to use Racket to complete a real project later.
I'm half tempted to try my hand at implementing zlib for Racket, but that counts as a separate rabbit-hole, and I'd like to finish the first goal before I start a new one.