This is why everyone is moving to Unreal Engine 5.
When you build your game around very specific engine (Forzatech) which is meant to serve a particular set of mechanics you’re gonna run into trouble. Its the same reason CDPR -an actual rpg developer- ran into so much trouble with the Red engine making Cyberpunk.
Now you take something that has only focused on cars, natural environments, and speed, and now incorporate human, monster, animal animations and AI, other story prompted scripts, far more interactivity with objects, and just a bunch of other mechanics into it, things are gonna get messy. It’s an engine that looks very good and serves very specific functions, so to build on top of it is gonna be an ordeal.
I think if they haven’t already, they will bring in Obsidian, InXile, or BGS to help