Two-Weapon Fighting (4 arms, 2 two-handed weapons)
 

I am trying to figure out what the attack bonuses look like for a Kasatha wielding 2 two-handed weapons. I made this chart to help me talk about this question. It assumes Kasatha Fighter(12th) with a BAB of 12 and no other bonuses to hit.

The numbers on this chart were taken from Hero Lab, I am trying to figure out if it's listing for the 2 two-handed weapons is correct.

According to the wording in the "Multiweapon Fighting" feat, creatures that have more than two arms, "It has one primary hand, and all the others are off hands."

What do you guys think?