FBI lacks jurisdiction in foreign countries and would only be there in an advisory capacity, like what the FAA does when it investigates certain aircraft accidents in other nations. Furthermore, the FBI and other domestic intelligence agencies have far greater concern with ISIS affiliates and Jihadists in general since, unlike incels, they have a coherent international organization and the sine qua non of Islamist extremists is to cause as much devastation and death in the west as they can. Finally, it is genuinely hard to make a case for conspiracy, which is what so many terrorism prosecutions are based on and your posting some diatribe in these forums will just not suffice as constituting enough probable cause for a warrant.