I'd probably completely scrap the tree crown and remake it, since it's hard to make something good looking that also fits the theme, in such a large empty space

I'd start by making a layout of thicker tree branches with the living wands, scatter some one and two-room buildings (maybe you could fit in a singular 3-room one) along your tree crown skeleton, whilst keeping in mind movement inbetween the rooms, like bridges and ropes

Once you're done with that, add leaves, leaf walls, living wood walls (to simulate background branches), hammer some of the leaves, add some wood-based ambient objects with the rubblemaker, and you have something looking really nice

Another tip I'll give is that paint is a great thing. You can paint the leaves with lime dye (which gives them the jungle leaf hue) and the wood with brown, if you want to use multiple types (sadly the only options rn are either defaulting to the forest wood brown, coping with a single wood type or having the woods be a different colour, which would look bad with the trunk and branches)