While not exactly trebuchets, you should try the 'behemoth drone' unit, it outranges turrets and rifle servos and can gain splash damage from the 'explosive shots' tech at factory. My favourite way to seige buildings at long range is a dual volley pod champ servo with missile damage boosts or cooldown reduction to missiles.

yeah behemoths are basically laser artillary - the unit limits maxes out at 105 which is pretty standard fare now in days and money game can be increased by supply units

I'd really like to see higher bloom ammounts though as 2k is very low in my opinion I'd rather see more resources on the field then the rest (and by more resources I don't mean types I mean just more of the one thats in game either more blooms - reloading blooms - or higher caps