Aeria the custom script is reloaded, so it might appear as the AI Script is loaded first. Looking at the heatmap of the script loaded on scene change and Handy movements though, it looks like the custom script is loaded.
Not sure exactly what you are saying. I'm not sure if you think it just looks like the handmade reloads or that it is loading for the first time.
I can tell you that I have watched MANY scripts that have a handmade script for the scene but the AI one loads. I know because the scene will have the girl touching the dick and the heatmap show nothing and the Handy not moving. So I look and then the handmade one loads with now showing that it should be moving. So I back up and it does move after loading the handmade script.
Good luck, I'm sure everybody has wanted handmade to come on as default.