As for me
Drop the use of the cluster tables for Ultras, they simply have a +1 to hit penalty (perhaps +2) If you need an 7 to hit then the second shot will hit on an 8 or 9...
As for RACs they also drop the Cluster table and for every two shots above the first adds a +1 to hit (1st shot +0, 2-3rd shots +1, 4-5 shots +2 & 6th shot +3)
All Ballistic weapons (sans MGs) have a +1 bonus plus an extra point for every 5 dmg or faction their of they do, as a bonus when calculating for the knock down check. This bonus "damage" is not actual damage, only for the purpose for determine if the targeted unit needs to make a knock down check.
As such an AC-10 will have done 13 damage for the purpose of determine if it contributed for a knock down check, as such if a Large laser also was used that turn and hit the resulting damage would be 21 as such such the targeted unit would face such a role.
As for the Ultras Jamming, well I would say for games set in the 3030s to the 3080s they jam as normal rules, after 3080 they can be unjammed.