Having most (if not all) important decision done on server-side is a flawed model. There is NO possible way to fix it fundamentally. By definition the server can never have the most up-to-date information regarding a player's status, so some of the time it has to be wrong. For the server to always have the correct information you'd need the ability to teleport data. The only workable band-aid is to increase the time it takes certain abilities to fire to compensate. This is why virtually every MMORPG has the client making most of the important decisions, not the server. The server doesn't try to 'predict' or 'compensate' information it doesn't have in other MMORPGs. All it does is let the client answer these questions. This makes the game slightly more vulnerable for hacking, but as can be observed by empirical evidence, there's no reason to believe FF14 is hacked less than any other MMORPG, so it's obviously not that big of a deal either.