First rune, TN 100: Ath 69 + 17 (Sub) + 14 (invokes) = 100, 2 FP and a Supp burnt plus maybe another FP or two for rerolls.
Second rune, TN 80: Ath 69 + 17 (Sub) = 86, second Supp burnt.
Third rune, TN 80: Ath 69 = 69, take 8 stress, be dead or Severe'd without rerolls or more invokes.
Fourth + fifth rune, TN 80: Akatsuki dies.
I get what you're going for with this analysis, and I do think simultaneously big bombings might give good outcomes, if we can be confident they'll all go off at the same time in exactly the same space.
But. I think the assumption that the best that they have to work with is two regular substitutions is fundamentally flawed. I know that this is all just to give us an example set, and even ath 69 is a guessed approximation of their skill level (though for at least Kisame, I really wouldn't doubt if his base fundamentals are at least this high). But, like... I would argue that anything that doesn't assume a team of S-rankers, comprised of multiple seal masters and jutsu hackers, don't have things equivalent to SotS at absolute minimum is not gonna work out for assumptions.
After all, that was a powerful reactive supplemental technique we got from a single former member of Akatsuki, and one he was willing to give away, so not a core part of his kit. So, for the first alpha strike, it may look more like
First rune, TN 100: Ath 69 + 17 (Sub) + 21(3xSotS) = >100, two Supp burnt, unlikely to need rerolls statistically.
Second rune, TN 80: Ath 69 + 14(2xSotS)= 83
Same for 3 onward, for 2*AB SotS uses.
If we assume SotS is level 40, which seems very low and reasonable for an essie with elemental investment, then there's still 5 tags left. That's dodging three and four, and maybe a single invoke or lucky roll on 5. At that point, that's the zone and all flatly contiguous zones unless we double up. Which I'd recommend, based on these numbers.
I'm not saying they have this ability. I am saying that any modeling we do needs to be based, at absolute minimum, on the most busted BS we have access to or are aware of. This is especially true for, example, Kisame. We know he has chakra for years (as opposed to days) and best in class jutsu for each niche. I'd be going in with the assumption he's got a reactive supplemental that trades being very inefficient (which he doesn't care much about) for being VERY good at moving or soaking damage. He can be overpowered. But we need to make sure we are actually using enough power to do it. One TN100 and four 80s I don't think gets us there.
(This doesn't include stuff like whether Itachi's jutsu reflective mirror would do anything, though I don't think it would as presented? Still, an assumption to state.)