Considering that you haven't even been able to use them since that point unless you've been using a really old version of the game, I don't expect you'll miss them that much. About the only way to recover such designs is to use them in a 1.1 game, then try to load that save in 1.2. *If* it works, you can then upgrade and resave them to get them in the new format.
Yeah, I also intended to do that, but since I'm having ToA now, those ships might have to wait for some time.
Thanks for your assistance.