They dont heaviely script HoI IV like they did with HoI III and rather guide the AI via the national focus tree. If you choose the historical gamemode they wont railroad it with heavy scripting like with HoI III, but rather weight the AI towards historical decisions.
The problem with HoI III was, that the AI had alot of problems with invasions due to the transports. Now that seperate transports that you have to built are gone now, partially due to that problem, the AI can do naval invasions much better now.
For those who dont know, transports are gone and you rather use your convoy´s to ship your units oversea.