Everyone knows it's not not easy to handle many Impact XT instances in the mixer console. My suggestion would be to manage the Impact Instances in the same way as the Inputs and Outputs. This already existing solution works fine, you can scroll horicontaly with mouse wheel and you can adjust the horicontal area to the left or right.
But of course, if there exists a better solution to this problem, I will be happy as well!
Look at the picture of what this suggestion might look like.