Terra Tina Kefka Cefca

[Peter1986]

It may not imply any particular pronunciation in some languages, but we are talking about the American translation here, and a C that's written before the letters E, I and Y is typically pronounced as an S, so writing it as "Cefca" for an American audience is unnecessarily misleading - that spelling would have been more fitting for a Latin audience.

Some changes make a lot of sense, yes, like changing "Pearl" to "Holy" and those kinds of things, but changing "Kefka" to "Cefca" just seems pointless.
Also, the original Japanese pronunciation is "KeFuKa" anyway - you can see that very clearly in the Japanese version if you can read Katakana - so "Kefka" is a perfect American spelling, IMO.
"Kefca" and "Kefcka" would have worked fine as well.