When designing the back end generators, provide a way custom generate a VM using Graal and LLVM optimized for the language. With the above project it might now be feasible to have own VM generated along with just targeting existing VMs.
LLVM may be a bit hard than Graal as Graal has Truffle. You will just need a AST interpreter designed on top of it with further customization based on the implemented language.
When designing the back end generators, provide a way custom generate a VM using Graal and LLVM optimized for the language. With the above project it might now be feasible to have own VM generated along with just targeting existing VMs.