These are all potentially very interesting narrative problems (which, perhaps, could only be overcome by an absurdly powerful god-like AI integrated directly into the state apparatus, perhaps some kind of "core" which we would assign a first-rate signifier on some kind of scale of effectiveness...)[/li][/list]
But if a human bureaucracy finds a less than perfect census functional, if not preferable, why would an AI refrain from playing the same game?
The figures are whatever supports the AI's future goals. It can not only retcon the figures across the society, it can simply emphasize measurements that support its goals throughout a large number of potential situations.
It is, indeed, one of the most disturbing aspects of emerging AI technology. Why would an AI care about being accurate when it can easily lie to a high degree of verisimilitude? Most people would rather live in the AI's world than the actual real one, I assure you.