or a lossy compressed lookup table.

But in this case you is unnecessary if a mechanism can perform that part, and understanding then completely doesn't rely on consciousness. This is a bit weird way to think about it, but it seems to be a semantic difference

It's still the same argument. If the conversation is carried on your end by a bunch of if-else instructions, there's no consciousness to be found.

In the Chinese Room scenario, cards with Chinese written on them are inserted into a box.

Inside there is a man who doesn't understand Chinese but has a lookup list of which symbols to write as a response to every possible sentence you can write on the inserted card.

For anyone observing from outside the box it looks as if whatever is in the box is fluent in Chinese and can hold a conversation. But the man inside does not understand anything about Chinese.

This is used as an analogy to explain that machines, very much like the man in the box, do not actually understand the data they are fed, nor the data they output, no matter how human the response might seem.

It was an argument against the Turing test, which is about whether machines showing behaviour indistinguishable from a human is a sign that they can think.

The Chinese Room argument is that they must also show understanding of the data itself, rather than just human-like responses, to say that they think.

...but does the system that is the Chinese Room (the entire system taken as a whole) understand Chinese?

Any given sufficiently small piece of your brain does not understand English, does no individual neuron in the language center of your brain understanding English mean that you do not understand English? If that understanding is held in the organization and structure of the brain but not in the individual parts, then why can't the Chinese Room understand Chinese despite no individual component understanding Chinese? That's a surprisingly difficult question to answer in a coherent fashion without asserting that knowledge in an organic brain is magical in some fashion, and nothing else counts.

Wait until you consider the concept of philosophical zombies, which is all about pointing out the edges and contours of the hard problem of consciousness. The starting point of that discussion is essentially "Is someone who responds exactly like a regular person would but has no actual subjective experience conscious?" and gets stranger from there.

then I dont get the chinese room experiment either