It isn't tied to any specific scenario. Some features require the scenario to be altered to use assigned AI orders, but the AI itself will play the same with the stock and user scenarios - they are all ultimately made using the same tools with the same features available.
What AI changes should I look for? I started Capt Cav's revised Kursk and after one turn of play with the AI running the Russians, I saw no difference in "competence". Tons of Russian units occupying good defensive terrain changed into travel mode and just sat there. An antitank unit moved into a 3x minefield adjacent to German units and numerous arty units (also in good defesive terrain) also changed into travel mode and just sat there. I haven't run any additional experiments with standard Kursk scenarios to compare, but is this AI "behavior" due to my playing a modified scenario?