I didn’t place anything in the default saves folder.I first created my dynasty and then first thing after making my coach, skills, etc went to options and Commissioner mode. Exported the DB file and then whenu go to the saves folder, I click led that dynasty I just made and did the saves there by clicking the DB folder. Click that file and it will bring up the spreadsheets that contain coaches, players, etc. then u just copy paste over the real world coaches. Go back to the game screen and now import the same DB file and it should now contain the real world coaches. So you’re only changing field in that specific dynasty
I could be wrong but That error makes me think maybe it’s being saved to the wrong spot? If that’s not the case are you sure everything is copy pasting over correctly and in the right spots? I could see that throwing things off