Ah, Final Fantasy pronunciations before voices gave us them. It is fun trying to figure out how it was done.
As for what you've got, Sabin and Kefka are generally the accepted version. Mog is pronounced the second way, instead of the first (based on other games).
The general accepted version for Celes is Sell-ess, but after Square made Cecil into Se-cil pronunciation, Celes technically should follow that naming convention. Therefore, it technically should be Se-leez.
As for Gau, it should be the two syllable way. Gau is feral like you mentioned. A two syllable name would be closer to a feral sound than a real name. I do get why people would use 3, but that's taking the feral concept a little too far.