Noticing this as I'm attacking Rome as Carthage. They're playing uber-defensive and moving armies to wherever I have an agent, as if they're mis-recognizing the agent as an army.

CA recently discovered in warhammer 3 that this was happening in their AI there, and the AI in dei is doing the exact thing that it was doing pre-patch in WH3. This is worth you guys looking into. You can replicate by moving agents to a non-threatened border and watch as they pull troops from threatened regions to "counter" the agent.