is there a decent substitute for coconut oil?

You'll have to be able to press the dough out while it's cold so you want a fat substitute that is generally solid at room temperature. I was going to suggest butter but the recipe says that makes it crispy. But several other recipes I checked (including America's Test Kitchen) use butter so I'm confused. I wonder if ghee or results in a crispy texture too.

I haven't tried this, but a food substitutions bible tells me that frying or sauteing oils can usually be substituted one for another...this includes corn, peanut, olive, canola, grape seed, palm, safflower. Even olive oil and untoasted sesame, but both those usually have more flavor than the neutral oils and may change the taste of the final dish - date squares here.