Hello Sergio, I see you have done adjustments and you have a well expertise to get your printings in good condition, but I actually believe the problem is with the paper itself, I've seen that problem many times and I still see it sometimes. The humidity in the air deforms the paper, specifically on thin substrates like that, so once humidity gets there, you won't get rid of it unless you get a fresh and new cut of paper, and print it as fast as you get it in to your press room. That's the reason I tell the cutter operator to cut my material just before I'm about to work with it. In any case if get my paper cut but I won't use it soon, I cover the paper with something heavy to keep it as flat as possible. But why on the trailing edge? while the sheet is deformed by humidity, when it gets to the impression drum, and your sheet is taking form on the drum, any amount of air between the drum and the sheet, comes out from the trailing edge, when your paper is in good condition, the air comes uniform as the surface is flat, but when your paper has humidity and surface is not longer flat, the air in there doesn't get out of there uniform, marking that wrinkles. However you can minimize (but not solve totally) the issue by lowering the temperature of your Blanket, and if possible the IMP drum too!
I hope you solve it.
