Hi Jeremy, welcome to the forum
Good luck with your hunt for a coupé - keep your eye on the Marketplace section on here as well as the usual vending suspects. Bear in mind you need to have submitted 5 posts before you can send/receive PM's.
The sunroof glass has a bonded metal edge with a lip around which the exterior seal grips. It rusts over time, especially at the leading corners and front centre at the seal join. To my knowledge, although it's an issue for most owners, we don't have much progress to date in finding a solution unfortunately. Many sunroofs are now sealed shut as a result.
Due to the comparatively few numbers left I think a remanufacture would be extremely costly, however any further ideas are most welcome!