HOWEVER a single fade vs fade per tier would produce a very different effect. I can understand the bride being upset about this, its not what she planned for. I also understand her being upset about the late delivery. If I was her and went into the ceremony knowing the cake hadnt arrived I would be freaking - wondering if I was going to have cake at all.
To normal people a wedding day is just that - a day - a good day and a happy day as you are committing your heart and life to one person and accepting the same from them. But a bride is not a normal person on her wedding day. Nor will she be normal until she gets on that honeymoon and relaxes. So I understand her being upset and dramatic. This does not mean she is a bridezilla. Although I admit if any of my sisters behaved so dramatically as to not go into the store and speak with the cake decorator I would slap them silly. Some drama is acceptable but being a princess is not appropriate and does suggest she will not speak highly of you regardless of the compenstation.
I would give her the $200 gift cert or make it cash if she asks. but I would try not to part with anymore. At this stage it is compensation not a refund. She may (when she calms down) just want a monetary compensation to feel that you understand what your error caused and that you have given something for that error. Of course both of you wish it never happened and that you cannot fix that error but the $200 is like a fine for making the error.
I am sorry this happened to you and hope this is resolved quickly and without too much pain.