The dealership gave up on finding this intermittent water leak. After removing the headliner and putting this wagon under an indoor rainfall, we found droplets forming at the front seams of the panoramic sunroof cradle. Someone has been in here, and put black butyl on the area of the leak, but it was not a remedy.
We found bits of desiccated sealant at these seams, which seem to be factory weatherproofing. The seams flex allowing water to get past.
Rather than replacing the entire sunroof cradle, which would require removing the entire roof, we applied layers of silicone over the top of the seams. This silicone will allow for the minimal amount of flexing that goes on, but will remain water-tight.