Hi Jason,
What has happened to your hulls is called "low cycle fatigue". The deck of a catamaran hull is in compression bow to stern. The forestay is pulling up on the bows, the mainsheet is pulling up on the sterns and the mast is pushing down in the middle. This tries to bend the hull and make the deck get shorter which puts it in axial compression. Also punching through waves tries to bend the bows up which adds to the hull bending and deck compression problem. The maximum load, high stress area, is just in front of the trampoline, 1 to 2 feet, in the deck. After this has happened millions of times/cycles the bond between the foam core and the fiberglass skins gives up. The foam sandwich in the soft areas of the deck in your boat has delaminated, not glued together anymore; it is old and tired and just worn out. This is hard to fix. You have to rebond the inner skin to the foam and it is major sergury to get to it.
Here's a way to do it. In the soft area of the deck, grind away the outer skin and foam down to the inner skin. Bevel the perimeter of the ground away area back on a shallow slope. Replace the removed/ground away foam with a mixture of resin and microbaloons. Leave the microbaloon core about 1/32 inch low relative to the original deck around it. You can use the original deck around the repair to guide your squeegee. After this has cured, restore the top fiberglass skin coat and add a couple of extra layers this time tapered on the forward and trailing edges at least 1 inch per layer. The hull should have been built with additional fiberglass layers in this high load area in the first place but it wasn't, hence your problem. Paint the repaired area and you are ready to go sailing again and ready for another several million low cycle fatigue cycles.
Good luck,
Bill