I believe (as in I'm not sure) it was me who sketched out the original palette structure (but I did not design the palettes themselves), and transparencies were not on my mind as I did that.
Forest overhangs works, but on some of the palettes you're gonna want to use different colors to get the best results. I would suggest not using transparent water, as A) it would clash with our style and B) we've already got super sexy water. :3 But in all seriousness, using transparent water or not is up to every individual, but I do not believe we are going to have the tiles for it included with the set on launch. Unless one of us gets inspired and decides to do it anyways, but as of right now, yeah, I don't think so.