Perhaps add a library, upgrade s hook to a university, fortified walls as opposed to stone walls. Fortified gates that Include a defensive aspect ( oil dump, porcullis) l, horse drawn carts upgrade from wagons, horse as a resource for the barn that must graze and is used to suplly the horse drawn carts. A Fait/fair. Winery + wine cellar! May e a slight revamp on time it takes to craft crossbows or heavy tools.
Ability to set a patrol route for guards! Or have them patrol a radius around the combat flag location.
Better market income.
Some of these could also be tier 5 Ideas
Also perhaos a way to assign some labourers specifically to waste pickup
Religion could give a buff acording to what is chosen with unique pro ) con and structures associated to it. (Maybe some made up) or pick from main religions associated w the time ( Catholicism, Judaism, Muslim, Sikh, Christian, Buddhism, pagan, etc)