I agree that due to the nature of the treb as it is now is difficult to work with. However that difficulty keeps it balanced. Allow me to clarify, currently the treb is the ONLY siege weapon in the game and when used is predominantly used in offense. It’s extreme lack of accuracy gives the defenders a fighting chance. That being said “IF” other forms of siege weapons were integrated into the game that were more defense focused then it would be fair to make the UI and accuracy of the treb easier to manage.
There are some that would argue that boiling cauldrons are a defensive siege weapon, however the area of effect is so small its virtually impossible to hit anything with them. If the area of initial effect, splash radius, dam over time, and spread over time was accurate to real life physics then they would qualify as a defensive siege weapon and not just a decoration like they are now.
To be honest for an age of “WAR” very few features added represent actual warfare. Here are a few things that would have made sense.
Offensive Siege Engines-
Ballistae, Battering ram, Deployable FOB, Siege tower (wheeled tower for assaulting over walls), Catapults.
Defensive Siege Engines-
Ballistae, Motes (Spiked or flaming), Spike traps, pendulum traps, poison dart traps, stationary catapults, and siege cauldrons (with improvements mentioned above).