Is there a way for the reminder text to find a card characteristic? Rather than say "whose converted mana cost is equal to this card's converted mana cost" on each card with turbulence, I just want "with converted mana cost 0" in this case, like on Tolaria West.

Not yet. At the moment you have to create one variant of the mechanic for each CMC you want to use it with. I note that Cascade didn't spell out the explicit CMC in its reminder text, though.

I do have an enhancement to the mechanics page planned to allow you to specify some "silent" variables like this which will get embedded in the reminder text where you specify.

Well, cascade was CMC less than that spell. This is exactly the same CMC.

I note that a land is a rather bad choice for a turbulence card, because most of the time the "card with CMC 0" that you hit will be another land, and most of the time you won't be able to play that card (unless you've got something like Oracle of Mul Daya around).

You won't? The point was that you got a bonus land when you played this, but it entered the battlefield tapped.

It lets you play the card in the resolution of the ability, but only if you'd otherwise be able to play it. In other words, it doesn't negate the need for an available land drop.