Did you not read the part where the Executor hit an X-wing, dead center at close range (<100 meters), from the side?
Yes I did. But Canon is pretty clear on the matter. Turbolasers can not accurately hit star fighters other than by luck, or because the fighter is traveling in a straight line, most often at the gun itself.
Hitting a bird flying past you isn't that difficult actually, not if you know how to lead a target. Hunters do it constantly. Turbolasers however don't have the ability to accurately lead a starfighter. So in the case of that shot it's most likely the fighter pilot actually flew into a bolt from the gun.
Given the fact that turbolasers generally can not track and hit a starfighter, again something well established in canon, so a few cases of it happening doesn’t really change anything. Putting an ISD into a game that revolves around starfighters doesn’t make much sense. The ISD would simply never be able to effectively target and shoot the fighters. This is simply not a matter that is up for debate. All canon sources agree on it. ISD's are not effective at shooting down fighters, that's one of the reasons they cary Tie Fighters. So they can act as a anti-fighter screen for the ISD.

