I don't like California as a name. But if she is going with that name. The best nn spelling would be Calli. Not
Kali. There isn't even a K in California. I just find it odd sorry.
I like the name
Cassia also but I do pronounce it cass-EE-ah. Casha or Kasha does look more like your pronuniciation in my opinion. I would go with Casha.