That is a good example of a possible fallback they could implement, as I suggested.
Yes. I'm curious, though, how they manage to do that with an extended downtime on their node. Do they route all incoming deposits directly to cold storage or do they route incoming deposits to the hot wallet and only move some of it to cold storage when it gets too big?I don't know how they route deposits and handle cold/hot wallet balances. They should also be able to fall back to other methods for checking on deposits. They know the addresses. I don't know if they have the keys for deposit address though without bitcoind, so they might not be able to move the coins. It would be interesting to see the details of their setup. A lot could probably be gleaned by a thorough examination of the blockchain given some known deposit addresses and withdrawal origin addresses.