Baking is hard—it's literally a science. If you put in just too much of one thing, the entire bake might as well just go in the bin. A lot of these home bakers learned the hard way... Moral of the story: patience is key, and read the recipe!
Cilantro in a cookie sounds awful. Some people like it especially topped on Mexican dishes. Others think it tastes like soap. Everything can agree that this probably was just awful.