my 2cents, kunena team work always hard to keep kunena to the top, very good but team have to think that there is a lot of users who have to do maintenance and upgrade from previous version to new one, and they should assure the maximum of backward compatibility, this is also the purpose of a good extension.
Yes, for years before Kunena, there was a "discuss bot" hack for Fireboard that gave almost the same functionality. But, actually, the Kunena Discuss plug-in is rewritten for Kunena and it *does* import data from the older hacks to Fireboard.
If you need help with importing your data, we're happy to help you. Just post in the Kunena Discuss section of our forum (I see you are registered, but haven't asked for help yet):
Hopefully, we can help you out!