We intend to soon deploy a hotfix that will make Season 4 crafted items corruptable using the new Contaminants. This will not change how they initially drop (they still won’t be initially Corrupted), but they’ll now be valid targets for the Preserved Contaminant.
This will, of course, exclude items that cannot ever be Corrupted, such as engineering goggles (Azerite) or alchemist stones (trinkets).
We’re still working on the issue of items that were cleansed prior to this new system. We’ll update you further on that in the next couple of days.