If I was the scriptwriter , I do not change the name of characters because I think it is a good name and have origin reasonably.
Jack Frost I think this name from Frost because his power is over the ice and snow . Nicholas St.North or you can call he is
North this name from he is Santa Claus and North’s home is in North Pole, it may be a reason of this name . Toothiana
because she is a queen of tooth fairy . E.Aster Bunnymund his name may from he is a rabbit. Sandy it from sand that he use it
to create a good dream. Pitch Black as black sand . And for the location I think it is all right because at North pole has ice
and snow which there are origin of power on Jack Frost . So if I was the scriptwriter I do not change anything.