From my understanding LLVM's intermediate language is at a "lower level" (which is the LL after all) than the .NET CLR (or the Java JVM), losing some higher lev

From my understanding LLVM's intermediate language is at a "lower level" (which is the LL after all) than the .NET CLR (or the Java JVM), losing some higher level parts of type understanding and looking a lot closer to machine language. You'd have to reconstruct or synthesize a new understanding of the "lost" high level information to target them as an LLVM backend. It sounds like Rust's internal MIR intermediate language is a somewhat closer level match to CIL.