Could it be possible for, like, you to close the servers for a bit and update everyone's accounts to use the new method of storing trinkets and stuff? Or is that not really something you can do?
Viewing post in Upcoming account/save data changes comments
unfortunately not, since trinkets are stored in arrays now as opposed to DS list strings (like "2FA100001245678"), and level records are now 2D arrays as opposed to structs. that would be very complicated to convert, so while it's annoyingly unfortunate, it's a little safer to just leave the accounts as is and let the game do the cleanup. (most people playing unfortunately can't access these records now anyway and are probably already gone, so it's a bit redundant)