I tried creating a sqlite db and adding a new Date field to the issue class then creating an issue, setting some fields, and exporting the result. I was unable to reproduce the problem you're describing.

The problem you saw was on 'create' actions not dealing with parameters properly. From what I can tell, though, create events don't have parameters in the journal. If you look at the end of create_inner for the backends you'll see something like:

if self.do_journal:
  self.db.addjournal(self.classname, newid, 'create', {})

There shouldn't be any Date objects (or anything else) in create events to confuse the exporter. So I'm not certain how you're seeing what you are.

However, I did discover that it hasn't always been this way. A long time ago (the change was Nov 6, 2002 for the 0.5.3 release I think) 'create' events *did* store parameters in the journal. Is there any chance your database is that old?

I guess I'm at a loss how to reproduce your problem. From what I can tell, it shouldn't be happening with the current roundup unless you have some data from before 2003 :-/ I'm loath to commit a fix when I don't understand what is going on.....