Like maybe you get the LLM to try _really hard_ to churn through everything, but this feels like a big case of "perils of the lack of laziness".
Of course if you have a good idea for how to deal with allocations etc "idiomatically" already maybe that works out well. And to the credit of the port guide writer bun seems to have its explicit allocations that are already mapping pretty well to Rust.
My only experience with ports so far is Python to Go, and it's been near flawless (just enough stupid shit to make me feel justified to be in the loop).
Especially for memory management the right and wrong abstractions in Rust can lead to a factor of 5 or 10 extra amount of difficulty. The right memory management abstraction and your code can be a straight line port (or even cleaner!), the wrong one and you're going to just be spending a lot of tokens to have a machine spin around in circles trying to untie itself
GC'd languages don't have this problem, though obviously you can still generate stupid amount of pain for yourself by doing something wrong