Important is also how complex and interesting is the climbing structure. For example, introduce thinner ropes, hoses or artificial lianas in addition to thick beams.
Also, apes seem to dislike strong sun and like shade.
It is best if zoos check publications how wild orangutans actually move on trees, and make climbing structures which allow the same types of movements.
Several zoos made swaying poles, which mimic how orangutans sway trees forward and backward to move between them. Orangutans apparently like them very much.