Very interesting, as usual! I wonder if the British usage of
Sunshine, and sometimes
Sunny, is in any way connected - the sound is the same, and sunshine is warm and cheerful and would make a good nn;
Sunshine can be used as a filler when talking to someone whose name one doesn't know, but then it's usually a bit condescending or disapproving, in the same way as
Pal or
Buddy can be.