AI calculates its power by tiers of units, quantity and types of units (cav is +50% power). Power is represented by the green-red bars on the strategic map and actual field battle / siege. Esentially if enemy army is running away from you its gonna be defensive, if it is running towards you its gonna be offensive. It is going to run towards you only if it has more power than you. This all applies in both RBM and vanilla, we disabled the defensive tactics for attacker AI to avoid situations when two AI commanded armies might just camp corners of map.I'm currently reading your mod's description on Nexus, and will try it. It looks like you're trying to help the devs fixing the game, it's cool.
Cause after several hundreds (even above thousand) hours of playing I'm clearly deceived by the battles (and unconsitant forest maps).
+ lately looks like the AI never attack and will settle for cowardly-mediocre turtling. At last, I attacked an army like I was 300 vs 580, and still they were not attacking. And I checked their units, they were not (the IA) having like 200 recruits, which could be a matter justifying the non-attacking behaviour.