If someone had totally broken the hash in secret, I doubt they'd burn it on such a low-stakes canary.

the canary is there for a gas leak, not for an asteroid destroying the earth.

the canaries that are left are worth several million of USD combined, if there's any incremental progress towards cracking them, that's a strong incentive not to leave the money on the table.

if someone comes up with a full crack sponteously, then yeah the canaries won't protect you, or anything else for that matter.