We fixed a forking bug, and they called it a "rollback" though it really wasn't that in the sense of someone deciding to reverse anything. To be fairm fixing the bug took quite a while and during that time a lot of blocks got mined onto an invalid chain. Nevertheless, only a few transactions ended up breaking (most worked fine on both the good and bad chains).
I think cryptopia's issue had something to do with their database being unable to handle the long reorg that occurred once the bug was fixed. Perhaps they'll have some way to address it going forward and can reenable the coin. We would welcome their support.