I think you're right. My hope was that it could reason through the problem using knowledge from related sources like C and an understanding below the syntax of what was actually happening.
Depending on what you're doing, you might find few-shot techniques useful.
I used GPT 3.0 to maintain a code library in 4 languages, I'd write Dart (basically JS, so GPT knows it well), then give it a C++ equivalent of a function I had previously translated, and it could do any C++ from there.
But it most certainly did not.