Is there a competent chem lab working on this? If the problem is that obvious (visible damage to exposed copper pipes) then the effect cannot be very subtle and a couple of good chemists ought to be able to figure it out in no time.
Figuring out what is outgassing, wet and dry, should be pretty simple.
This might require the resources of a high end like at one of the National Laboratories (Argonne or Oak Ridge), but this is potentially a mult-billion dollar problem and the EPA certainly has access to them.
The state of FL has very good chem labs working on this. My company is working with the same lab.
You are quite correct, IMO, that a simple chemical reaction should be figured out quickly. Since it hasn’t, my suspicion is that it isn’t simple and therefore not purely chemical in nature.
I’m presently leaning to the hypothesis that it is a combination of contamination with bacteria and/or mold combined with poor humidity control associated with negative building pressure. That might explain, to some extent, why the problem popped up first in the most humid areas of the US.
This is how I get most of my exercise: jumping to conclusions.