Have you read everything that the nobles have to say about Neretzes' folly? How an emperor took the worst possible decision and got defeated from it? The way I see it, the AI should not be a perfect war machine making all the correct choices. Maybe they started a war with the Aserai over some pointless personal quarrel, for example. It's not like it's an outlandish idea; it's happened in history before. So I'm fine with the kingdom's AI making questionable decisions (as long as they are based on something tangible, like terrible personal relations with a ruler or noble of another clan, not just RNG).
Instead, the player should have a way to influence these things. Is your faction's ruler an incompetent bastard? Use your influence and plotting to make them disappear, and take over instead.