Would it be too difficult to keep a state for every badge that you update when a new checkin happens? You'd need some specialized logic for every badge, but not much more complex than you already have. Depending on how much space you save it could be worth it.

E.g. for "you've seen foo 4 times today" you'd keep a list of the foos visited. When a new foo comes in you first remove the foos older than 1 day from the list, and insert the new foo. If the list now contains 4 foos you award the badge.

You can use a bitvector to record the badges that have any active state at all, so for badges that have no state associated with them yet (e.g. no foos seen yet) you only pay 1 bit. Or if very few badges have active state on average you could use a list of badges that have state instead of a bitvector, so that you only pay for badges that actually have active state. So total storage is 1 bit per badge or less + a couple of bytes per badge with active state?