The ticket credit currently resides with the person to whom the FL ticket was assigned in MDE. If you manage that person's profile, you should be able to call WDW and upgrade the ticket (to non-resident ticket) then transfer it. If you don't want to do the upgrade yourself, you'll still need to call for WDW to transfer the credit.
FYI... it doesn't really matter if the credit was for a FL resident and the new ticket will be regular. It's a credit towards any new ticket.
I'm a little concerned that if I call to change to non-resident I'll lose the access I currently have online to transfer the ticket to the non-resident who will use it. (Stranger things have happened.) I walked through the process, though, and it appears that you can't change the residency status of a ticket online through MDE so it'll have to be done at some point. Or is that something that can handled via chat?
I also don't want to get into "you're not X" and can't get handled on the phone. I have access to all info for both parties (they literally have no idea the ticket exists, lol) and it would be a real pain to get either of them involved to call guest services.