"Pointless tile 1,19" <-- Not true, you can use it to add shine to some tiles. Although the application of the shine is very limited.
"No opposite version of tile 8,40" <-- Theres an opposite version at 1,40, it just needs to be lighter.
"Tiles around background trees that aren't needed" <--- Just about as unneeded as tiles saying "Tileset conversion by (Insert author name)"
"Diagonals at the bottom of the set don't join to the main tiles" <-- .... Yeah they do:

"Pointless tiles under the top half of textured BG" <-- Actually they match right up with the mountain reflection tiles, perhaps some unfinished sky reflection? It looks alright in the Parallax view in JCS, but pretty lame ingame.