WARNING: SPOILERS AHEAD!
So, I watched a preview of the unnamed Rayona's backstory episode on my laptop (Kidding. It was all in my mind.) and it looked like that:
A toddle-aged Rayona is sitting with her family and a giant made of meatballs in a greyish-blue room. The meatball giant said "That's why I suggest that you should this little one's name into 'Rayona'!". Then Nicole (I guess) asked "But why?". And then the meatball giant said "Because this name is more suitable than-". When he was about to say Rayona's real name an earthquake took place.
And that's all I can remember. What do you think guys?