Also, looking back at the photo, I'd want to know about the root systems of the trees. In my casual unfocused years of wandering the web I don't recall pictures of terraces with trees in the tropics. Would there need to be tap rooted trees just below the retaining walls to anchor the wall against the weight and expansion force of roots in the next level up? Or is it the other way, need tap rooted tree at the front edge of the terrace? I've seen many trees that have, very slowly, over decades, blown out retaining walls, heaved sidewalks, crowded foundations etc. I don't have any direct personal experience with terraces but I have dealt with the implacable hidden force of tree roots over the years.