The issue with calling it "the same problem the entire rest of the game suffers" is that even with lag spikes, I can dodge Weight of the Land by moving before it. You can dodge pretty much anything by moving right before it happens. I think it would be weird for this to be the only fight in the entire game that you're expected to dodge with no AoE zone, no marker, and the server picks when to place the thing you're supposed to dodge randomly.
Just to make sure, let me confirm the prevailing theory. You're saying that, due to the game only updating every 300 ms, there are times when your position has not updated yet and so the server places you where Twister is supposed to detonate? Or is it due to lag spikes that the server places you where Twister is supposed to detonate? If it's the former, I really don't think SE would tune the fight so much that their update frequency — something unavoidable and built into the game — would cause you to die. If it's the latter, then why is it happening in every Twintania fight at any hour of the day, despite Turn 4 being the least-played instance in the entire game (by virtue of being the very end of end game) and different players have it happen to them each time?
I noticed that when you got hit by Twister, it was just the detonation. Twister didn't place a black circle underneath you that detonated half a second later, which is what you would think it would do if you were expected to "drop" Twister somewhere. When you all tried standing still to eat it, was it the exact same animation as when you were running? As in, no one had a black circle appear under them that then detonated? It was just detonation?
Things to look for:
* Is it always the same people who get targeted?
* Is it always the same people who get insta-killed?
* Is it always the same player on that position in the hate list that gets targeted?
* Is it always the same player on that position in the hate list that gets insta-killed?
* Have you tried killing the adds at the same time?
* Have you tried killing the adds in a specific order?
* If you notice, the adds are called "The Scourge of Meracydia." Meracydia is a continent to the south of Eorzea that is the source of a handful of goods. Have you tried using some of these goods in the fight?
- - * Dark Bass (made into Bass Ball)
- - * Aloe (made into Forest Miq'abob)
- - * Angelfish
* Is there a relation between the people targeted with the adds' "Liquid Hell" move and Twintania's twisters?
* Is there a relation between the people targeted with Twintania's "Conflagration" and its twisters?
* Is there a relation between the person at that level in the hate list (A through 8) for Conflagration and Twister? I.E. Does person at level 4 always get targeted?
* Have you tried running exactly away from Twintania?
* Have you tried running exactly towards Twintania?
Obviously some of these seem obvious, but it would be good to get video proof. That way, a group isn't going, "Yeah we tried running towards it! Duh!" when in reality they were mucking it up.