Fix the cliffs?
It's actually really hard to do what you guys are asking for if he is using RPG Maker 2000 or 2003.. especially with that tile set, you can't make variations in tiles cause there is no room in the tile set, really he's got what he can use, unless he takes the tile-set and opens it in an image editing program and deletes tiles he may need on other maps, just so he can add more variety in some cliffs.
It's like telling the guys who made the SNES Final Fantasy 4 that the cave walls all need variations, it's just the style of the graphics really, especially if he is going with a snes feel, as i recall there was not a lot of variations in cliffs.
And if you think those graphics are square, wait till you see the games that can be made in VX Ace... they're all squared.. and to make it not squared is almost impossible..... just wait till games made with Ace come out *shivers* it's as if they are forcing the Dragon Quest style on everyone lol