When i choose cumans I can’t build Siege Workshop and Battering Ram in the feudal age.It just locked. But it is a civilisation bonus of this civilization ( Siege Workshop and Battering Ram available in the Feudal Age). My friends have the same problem.
build a blacksmith first. sorry. guess its not in the tooltip.
the tech tree has it though. build blacksmith to unlock the siege workshop. https://aoe2techtree.net/#Cumans
U can maybe install this improved tooltip mod, shows better and more useful info in tooltips for all units techs buildings (attack bonuses, armor classes, other stats etc… special effects or requirements )