[s1artibartfast]

>Perfect performance would simulate semantic understanding, no?

The thought experiment argues the exact opposite. The idea is you can have perfect Chinese but not understand a single word of what you are saying. The argument is that syntax (procedure based operation) and semantics (understanding) are distinct and separable.

As you extend the scope of the Chinese room from a single task (e.g. Chinese conversation) to human behavior in general, it converges with the question of if philosophical zombies can exist.

In terms of the Chinese room, the distinction IS the difference.

[fragmede]

That's what Searle's argument is, but it's a thought experiment and there's no consensus among professional philosophers as to whether or not to believe it is true.