I hope you can figure it out. I lost a Kirby and Donkey Kong Classic profile when it errored and I didn't know. Maybe adding a Backup folder to the 3dn folder that increment backups up to 5 or 10 copies back. It doesn't immediately error out when things go wonky so it's very easy to save the 3dn thinking it's all good only to have it break on load.
- Martin