This is a very interesting read, and is a surprise to me if this stock is indeed 8 years old and no longer made, but i guess that could explain why some people report yellowing?

Im going to ask Wittner-Cinetec about this, but i expect they have already read these posts.

As far as light piping goes, this film is very bad for light piping, and Wittner-Cinetec acknowledge this, my film displayed signs of this, however, it never affected my images, or made them yellow, just a little bit of orange around the sprocket holes.
I loaded my next cartridge in the dark, so will see if this helps, the only other thing that may be a factor is if the cartridges are not sealing the light out the best.