It turns out that my priest was simply misinformed regarding what constitutes valid matter, as surprising as that may seem.
My initial conversation with him is posted above in #19. The next day I talked to the woman who bakes the bread. She said that she was unaware of the problem, and asked me to forward my information to her via e-mail. She said that she would take the matter up with the parish council at their next meeting which was planned for the following day.
Two days later I received a letter from her. It stated that it was the goal of the council to follow canon law, and also to provide a host that "appeared as food." They said that they were going to change the recipe to the one used by the Benedictine Sisters of Perpetual Adoration that is approved under canon law.
A day or two later our priest came up to my wife at the first Communion rehearsal and apologized profusely. He said that he had gotten the recipe from a book written by a theologian. My wife said, "you know, you have to be careful with what you're reading, especially these days."
I was planning on calling the bishop's office that day, so I'm glad that I held back. It was a lesson for me in charity.
The good news is that first Communion will be valid!
Your family's situation was so much more dire than my family's situation.
You know, this is a good lesson on how we, the laity, can gently stand for what is True, and how a simple telephone call can change a dangerous situation.
Your daughter's special day is going to be beautiful weather-wise and it is so wonderful that you can go with a light heart (as opposed to a heavy heart) knowing that all the other children will have a True and truly blessed First Communion.