I don't think your idea is going to work as well as you'd like. Your idea may simply 'tone down' the noise to a different pitch but you probably won't notice a difference. In other words, the 'energy' from the sound waves will sound more like a low 'D' note (with the lattice and vines) instead of a high 'C' (as it is now.)
HOWEVER, the brand escapes me now but there is outdoor sound-absorbing 'boards' that you can put up 'behind' your lattice right on the wall to help ABSORBE the sound. I'll search the WEB or hope someone else can come up with the name. In any event, you still need to know how to attach the lattice to the block.