Alffe, I'd replace the copha with something else.

Copha is a solid coconut oil. 100% fat. 98% of that is saturated fat.

It's traditionally used here in things like chocolate crackles or white christmas treats because it's melted before mixing and then it solidifies when it goes cold.
I don't know why they have put the copha in the muffin recipe really because you're not actually trying to set rice bubbles as one would in choc crackles. Then again maybe it's the coconut that gives them their unique flavour.

For muffins I guess you could just use butter or marg or a pure organic virgin coconut oil or what you call "shortening". It's a 1/4 cup. I saw something called Dr. Schlinck's Palmin which is apparently the same as copha and maybe available in a good deli there, don't know. I wouldn't bother really.