To be honest, you've got me stumped on that one. I have never heard of a coconut flak. Coconut flake yes, but not flak.
it's in some of the recipes. maybe it's a typo? i googled it. i did find a few references to it, but not what it actually is. weird. maybe check those recipes and change the word if it is a typo.
i just figured out the problem. it is a typo. it appears several times on the iphone app. but the same recipe on the website says "flakes". you might want to make the app developers aware of this. thanks.