I think the mountains really need some little trees, even if fake, for the forced perspective and for overall aesthetics.
My big question is that while I realize that artificial grass will be used on the roof of Mermaid, what about the small little potted plants on the walkway and the vines? The concept art above for Mermaid doesn't look finished, maybe even fan made, are we sure this is Disney? (Though I think the Belle one and the overhead view one are authentic). I would add that the little "red" trees are in the film, and would like to see some more plants on Mermaid as it looks too much like a deserted island (plus in the film, Eric's Castle has stucco (or something like it) on the outside, instead of cement looking bricks).