Agreed. You would expect this to be a task that AI has a massive advantage over humans as it has both the testing suite to keep it on track and has the source implementation to reference. The classic failure case for agents is that as the task increases in complexity, it requires more steps to complete. With each step there's a chance for error. As errors accumulate, they become more likely. With verification functions, like test suites or comparison to some source, the agent is more likely to catch errors and recover.

So porting should be perfect conditions for an AI agent. It has the testing suite. It has the original implementation. Hell, it can A/B the original with its working copy and attach the original to a debugger.

So yeah I dunno. I guess despite some people's rhetoric on this site we shouldn't underestimate how difficult these tasks are "in the real world" (as opposed to like a game port which doesn't have real money on the line so far). And it is kind of a miracle these tools can even get in the ballpark and fool a lot of people.