Think of Rust as a kind of kernel guaranteeing correctness of your program, the rules of which your transpiler should not have to reimplement. This may be compared to how proof assistants are able to implement all sorts of complicated simplification and resolution techniques while not endangering correctness of the generated proofs at all due to them having a small kernel that implements all of verification, and as long as that kernel is satisfied with your chain of reasoning, the processes behind its generation can be entirely disregarded.