> But what makes a human mind more "understanding"?
If you view understanding as knowledge + the ability to apply it, everything falls into its place. The Chinese room can't apply the knowledge that it has, even theoretically.
The immobile Chinese room was once a mobile Chinese room.
You're refutation isn't there. There isn't anything that distinguishes a Chinese room from a Chinese person. You submit Chinese text and get Chinese answers.
You say understanding only exists in humans. That's special pleading not an explanation.
Ask your Chinese room what left and right means. Also: near and far, heavy and light, hot and cold. When it comes up with definitions through other concepts, ask what those things mean, etc.
Leveraging ability gets you nothing.