I found a post by someone with the same issue hes also in 4A. I guess this changes my above insulation plan?
From the linked article:
"My thought is that the water table level has risen or that warm humid air is rising up under the porch and bay window and condensing.
Does anyone have any experience in this, could confirm the reason mold may be growing, and the best way to remediate or insulate."
Without an air barrier to keep basement air from crossing over to the cantilever in winter moisture will accumulate in the cold plywood.
With an air barrier blocking warmer damper air from crossing the foundation into the cantilever and dense fiber insulation to limit the rate of convection loops for minor air leaks in that air barrier the amount of interior moisture finding its' way to the plywood is de minimis, and the moisture content of the plywood won't reach mold-supporting levels.
It doesn't change the plan.