The big problem with PC or Acrylic material is that it won’t support any level of stress if it wasn’t annealed correctly. This is the exact same problem with our F430 headlights. The webbing or cracking effect is called "crazing" and is caused by the stress applied on the part. The simple fact that a PC part is glued on another material like ABS will already create a level of stress on it. The solvents used to glue it will increase even more this level of stress. It means that the part can start crazing on itself.
Add to that the fact that the pressure at high speed on the headlight covers is huge! Crazing happens because the annealing of the PC part was not done correctly after it came out of the injection mold. If the crazing is not too important, there's still a chance to do the annealing process again but it has to be done in a very precise way. Depending on the thickness of the PC part, it must be heated for several hours in an oven (usually 2-4 hours per inch of thickness). For PC, the temperature is usually 135C/275F. For Acrylic, the annealing temperature is much lower at 82C/180F. The part must be brought at the maximum temperature at a rate of avg 25C/75F per hour. The most important stage of the annealing process is that the part must be progressively cooled off during several hours at a rate of avg 10C/50F per hour.
Some owners succeeded to remove some of the headlight webbing by heating it with a heat gun. What I wrote above explains why. But the crazing will come back very fast because heating the PC cover just with a heat gun is not going to anneal it.
All the older cars seem to have problems with the "old style" caps. On my car, I noticed that the clear disk was separating and falling off of the center cap. I just purchased a set of the newer style caps. They were about $120 and they look much better. Don't even think about the issue, just get new caps, it's the cheapest repair that you will do on a Ferrari!