as i previouslly wrote byzhantum development(as ai) has the following pattern: goes fast at war initially smashes usually all the minors around for first 30 years; then it gets quiet some bb most times and gets dowed by hungary after 1450 wich weakens him considerablly and then by around 1500 caliphate finds its way to bosphorous....an ai event that gives about 10bb reduction might work towards its stability in 15 centuary; also maybe a few ai events that increases land tech; personally i increased A LOT all the military skills of its monarchs in the monarch's file but still same thing happens.