Keys-tis would make sense for anyone who has ever studied french

It definitely makes a lot of sense for it to be pronounced that way. Not to mention it's easier to say and a lot easier on the ears.

[edit-- FF8 was supposed to be a 'western' game, so it would make sense that the names would be picked from more western countries, rather than japanese sounding ones. Of course they do that anyways, but more extensively in ff8 Quistis is frenchy in origin, someone above mentioned how germanic Seifer was. Squall is already an English word, and Irving and Selphie is very close to an English name. Rinoa is the token asian character, and Fuijin and Raijin apparently are based off of some japanese legend.

But then you have Quezacoatl, who is Aztec in origin, and never seen before (or since) in the series, Doomtrain, who is a freaking train for obviousness's sake, and I just suddenly wondered why I'm typing this all. Never mind.