On the Diplomat animation, I've tested this in a few campaigns, what it seems to be, is that diplomacy is bugged so that AI factions cannot initiate diplomacy other than to as for alliance, trade rights, or ceasefire/become vassal. If an AI diplomat is doing the animation to my town or diplomat, I'll send a diplomat to initiate with that faction, offering some token offer without demands. Most of the time you'll get a counter offer from them stating what they really want from you. I'm hesitant to go with the idea that this "bugged diplomacy" means an imminent attack, because when it happens in my campaigns, it is usually my allies that do it , and they usually want me to attack one of my neighbors that they are at war with. It seems that the AI cannot initiate diplomacy to ask you to attack their enemies, but can counter-offer it if you initiate the diplomacy (BTW I've made good money and even gotten settlements out of attacking an ally's enemies, it's also a good bargaining chip to get one way military access to their lands )