] First names are equally fluid with some countries tending to spell them in a particular way. for example, Catherine and Katherine, both of which JA uses in P&P (Catherine de Bourgh & Katherine B. - the contraction "Kitty" is rarely used for Catherine). Catherine is predominantly a French spelling whilst Katherine is the more English spelling.
While I do not disagree with your excellent statement on the differences in name spellings, I do believe that Kitty Bennet's first name is Catherine, not Katherine.
I find the differences in spellings to be quite interesting...very fun topic! :)