I don't find the Chinese room argument convincing in the least. After all, it's the software that does the understanding, not the hardware. Otherwise, it would be like asking my fingers to understand this comment, or even asking my brain, when it's really my mind that's understanding.

Speaking of rationality, it's probably safe to say that you will end with a sometimes irrational program no matter what you do. Neural networks have glitches, configuration spaces have local minimae, software has bugs. It's as if you saw AI as being "programmed" via a series of rules, when it's more a grow process, arising from probabilistic dumb agents. Even if these agents were to be rational, the system could become irrational: I refer to the current economic crisis.