Wonder if it would be better to auto translate to broken rust, ie forcing the user to fix memory issues. I imagine that would lead to pretty big refactors in some cases though.

No. What comes out of C2Rust is awful. The Rust that comes out reads like compiler output. Basically, they have a library of unsafe Rust functions that emulate C semantics. Put in C that crashes, get Rust that crashes in the same way. Tried that on a JPEG 2000 decoder.