> That said, I'm pretty sure the Haskell runtime is very complex, so it might still be the wrong language.

While the Haskell RTS as a whole is a big (and marvelous) piece of engineering, it is not actually necessary to understand all of it to contribute some smaller patches.

The RTS is written in fairly readable and clean C code and it is possible to make local changes to e.g. the memory allocator without having to touch code in lots of different places.