“Santa” is also saint in Spanish as well. However, given the history with Portuguese merchants in Japan, that connection makes more sense. As for the kanji, it is actually a name in Japan, though, from what I found is usually masculine. So, it is likely a bit of a stretch with the name to make the foreign language pun work out.

I think the durian fruit connection might be the right one. If you open up a durian, the fleshy, yellow part looks a whole heck of a lot like the hair that is bound and standing up on her head: