The man in the room is comparable to a human hand, and the magic rulebook to a human brain.
This in the sense that we can easily retain human "understanding" by stripping away almost all parts of the human body or replacing them with fairly trivially made replacements, except for the brain.
In the Chinese Room the equivalent is the magic rulebook: We have no idea how to construct/replace it, yet people somehow handwave that away whilst simultaneously confidently asserting it does not understand anything.
That's irrelevant to what we're talking about, though. The point here is not to assert whether or not the room understands, but to emphasize that our methods are insufficient to demonstrate this. You could posit that the room understands, or you could posit the reverse, and neither argument can be refuted.
This in the sense that we can easily retain human "understanding" by stripping away almost all parts of the human body or replacing them with fairly trivially made replacements, except for the brain.
In the Chinese Room the equivalent is the magic rulebook: We have no idea how to construct/replace it, yet people somehow handwave that away whilst simultaneously confidently asserting it does not understand anything.