Anyone else having same issue?
I wouldn't be surprised if others have hit the same problem. I'm not sure if the comments are backed up anywhere on your system. They might be online, but whether they're currently accessible is doubtful.
I've asked around and unfortunately you're out of luck. I think it would have been the same even if you had only deleted a collection (rather than nuking the data) and obviously this isn't good enough for the kind of workflow you (and I) envisage. I've passed on these thoughts to Adobe.