I don't have any experience with Lua but looking around I think it should be easy to load the formation coordinator / node implementations as Lua files that can be hot reloaded without re-compiling.

Great suggestion! I've created an issue to keep track of this. https://github.com/sushrut141/ketu/issues/8

I will definitely look into this once Ketu gains more traction. REPLit like behaviour would help more people try things out.