You're playing one of the easiest factions (solid units which get even better, rich economy right in your heartland), don't care about historicity or roleplaying to self-limit, and you're complaining it's too easy?

There is no mod which can augment the AI. Playing on VH campaign difficulty is the only means of making them more aggressive. Have you tried the Win Conditions mini-mod? That might cause them to come for you if you tweak it right.