hmmmmmmm. Yeah, we're way out past the edges of my knowledge here (I'm just working from what we've seen before in the importer).
You can tell if an entry is backdated by editing it: if you're using the old update page, it'll be a checkbox near the date item labeled "date out of order" or "don't show on entry pages" (I forget if we renamed it there or not), and if you're using the new entry page it's in the Display Date panel and labeled "don't show on reading pages".
If it's always getting stuck on comments, I wonder if the script you're using just doesn't have good comment mapping error handling. Have you taken a look at jbackup.pl that Pau linked to above? Is there anything like that in the script you're using? I've never looked at it, so I don't know how well it handles weirdnesses. I know you've probably hit the point of "I've put this much effort into it, I'm going to make this work goddammit," but just to rule out issues with the script itself: if you try running jbackup.pl does it get stuck in the same place?
Re: well howdy
You can tell if an entry is backdated by editing it: if you're using the old update page, it'll be a checkbox near the date item labeled "date out of order" or "don't show on entry pages" (I forget if we renamed it there or not), and if you're using the new entry page it's in the Display Date panel and labeled "don't show on reading pages".
If it's always getting stuck on comments, I wonder if the script you're using just doesn't have good comment mapping error handling. Have you taken a look at jbackup.pl that Pau linked to above? Is there anything like that in the script you're using? I've never looked at it, so I don't know how well it handles weirdnesses. I know you've probably hit the point of "I've put this much effort into it, I'm going to make this work goddammit," but just to rule out issues with the script itself: if you try running jbackup.pl does it get stuck in the same place?