It would be spelled Cesca in that case (that's indeed a nn for
Francesca). I've never seen it in the spellings suggested by the OP (I'm well placed to know since
Francesca happens to be my name).
*BtN's resident 10th century Japanese novelist*
My lovely !!! are
Mehitabel,
Hypatia and
Zohar.
"In War: Resolution. In Defeat: Defiance. In Victory: Magnanimity. In
Peace: Goodwill".
Winston Churchill