You don't show it in the pictures but what about the fasteners attaching the panel to the PT board?
2304.9.5 Fasteners in preservative-treated and fire-retardant-treated wood.
Fasteners for preservative- treated and fire-retardant-treated wood shall be of hot dipped zinc-coated galvanized steel, stainless steel, silicon bronze or copper. The coating weights for zinc-coated fasteners shall be in accordance with ASTM A 153.
Exception: Fasteners other than nails, timber rivets, wood screws and lag screws shall be permitted to be of mechanically deposited zinc coated steel with coating weights in accordance with ASTM B 695, Class 55 minimum.