Bill G

We've had refunds issued to a different card that was used with Royal, but never to someone NOT on our reservation. For example, we typically use one card to pay for the cruise itself and a different card for Cruise Planner purchases. We've had CP refunds issue to the cruise card instead of the "original form of payment."

The cruise industry has made itself fairly bullet proof (legally harmless).  My wife has a lawyer who actually specializes in suing cruise lines (that's not what she has him for) and he says that it's almost impossible to successfully sue a cruise line (don't know if I actually believe that.  But, I'm not a big fan of lawyers anyway, and that after 20 years in Law Enforcement), EXCEPT for trips & falls (injuries) & things like food poisoning.  So, I believe, that getting a cruise line like Royal to pay you for your time is like pi$$ing against the wind, regardless of what a lawyer says.  But, you'll get nothing if you don't try!

During the COVID shutdown I had refunds for port fees and onboard purchases sent to cards that were not used for that particular purchase.  My dad and I had a cruise together and we had quite a time sorting out all of our refunds to make sure it was all correct. It's like Royal had a list of any card I've ever used with them and just randomly picked one to refund to. 

May be what we should expect but not what seems to happen with Royal.  As you seemed to have done, after a couple of weeks, I would have disputed the charge with my CC company and let them deal with it.

Unfortunately I had Royal refund a FCC (they did this without me asking for a refund) of over $2000 (yes thousand) to the wrong person's card, several emails, phone calls, and chat session ensued to no reasonable solution other than having to pay the balance of our cruise again.

It has happened to me but never to a credit card that wasn't mine.  I just check all my credit cards to see where the refund went.  I have learned with Royal you need to expect the unexpected.  I don't get too bent out of shape about it. 
I believe they have a weird accounting system. 
During Covid, I was told all the refunds were being done manually.   I have used different credit cards but the refund amounts never matched anything remotely close to the "original payment method".  Cruise planner purchases were consistently correct but not all the time.
I somewhat enjoy catching their mistakes when it isn't in my favor.  I just call and ask someone if it is correct.  They usually acknowledge the mistake and correct it with another mistake in my favor -- then I say it must be correct and I don't say anything!