Hmm no, its the Opposite actually, they dont target player , unless they are forced too. Tough luck, i guess your horde was on Roman land, so naturally your presence itself was considered as thread by AI. About the other part of their empire is getting crushed, i can say that AI make bad jugdement on handling their eastern front, basicly they will try to react to the closer and easy threat they can handle nearby, but since its was the AI from the game that was not update to much, (yes its still far from perfect)One question though : does the AI has an absolute priority to go after the player in the mod ? I say that because I had 5 full Roman stacks chasing my single horde army everywhere in Spain(very challenging), but their entire Empire was being crushed on the eastern front..
Like Sir Sharp already said, if you remove artillery from equation then you can say "bye bye" to siege scenario especially when dealing with walled settlement, tough choice hope future update will correct AI behaviourgood mod though, is there a submod that removes the artillery changes ?