> I want to dig into one of these editors for a stronger understanding of how they work, and using something as obtuse as Rust is a total nonstarter for me.

I would be absolutely amazed if the language is what makes an editor easy/hard to understand unless that thing is written in whitespace/brainfuck. In this particular case the helix codebase is incredible easy to understand and contribute to, definitely easier than vim, neovim and others _despite_ the fact that it's written in Rust.