Glad it all worked out for you. Too bad Disney basically shrugs at all the stress this causes people in what should be a greatly exciting time.
One question that I'm left with is whether their ability to reassign reservations can transcend the bucket system. For example, can I use your refund approach to hold park hopper reservations, upgrade a ticket to a Magic Key, and then transfer the park hopper reservations to my Magic Key? If not, can I do this while I'm a Disneyland Hotel Guest?
I have a suspicion that if they allowed E-ticket changes over the phone or internet, Disney or unsuspecting guests would be open to some sort of Fraud. Disney's unexplained "sorry, there's nothing I can do" line is deeply unsatisfying.
Numerous people have been told by CMs that you cannot upgrade a ticket with reservations to a Magic Key and retain the reservations. It is impossible. The upgrade will cancel out ALL the reservations and the advice is to do the upgrade on your last day AFTER you are done for the day.
That said, the hotel bucket functions as essentially a guarantee of getting park reservations. I have not heard one story where a hotel guest could not get in any day they wanted. And my own personal experience is that it's a literal guaranteed slot. Even when a day is unavailable otherwise.