There are no cyanotype recipies that have gallic acid. A number of them have tannic acid.
Yes, I just found these, actually, thank's for pointing in that direction. I don't think that the tannic acid / gallic acid difference would really matter, they seem to be similar enough ...

On a slightly different tangent, along with the copper oxide, has anyone thought about/experimented with replacing the silver nitrate in the Vandyke formula with copper nitrate?
Well that would make it a tad cheaper ... hmmm