I wouldn't know if it was meant to be like "Car"a or "Char"a, or like Chava with an r.
It could even be "Shara", like a rare nickname for Charlotte.
Kara and Cara make me think there's a 50% chance it's pronounced "Care"a instead of "Car"a, but I couldn't guess. The C version looks more like "Care"a to me but it could still be "Car"a.
Carys and Charis sound pretty similar when I say them. I like Charis better but Carys looks more usable.
Charissa is definitely with a "c" sound. The 'issa' ending sounds too prissy to me, at least in this case.