Going through that spreadsheet on mobile will be challenging so i’ll just have to look at it when i’m on pc. If your grid is at SL 20, how many of those weapon and eidolons are +99?

One +99 gives 396 extra stats. Assume half of your weapon and eidolons are +99, that is additional 2376 atk to your grid. Have you factored those +99s into your damage calc?

Also when i say your math doesnt checked out with facts where multiple people have posted that they do more than what you calculated. Have you ever considered that there is a possibility that the assumptions and formula you used are incorrect?