Are you deliberately being obtuse? G-12 is produced by several manufacturers... Motul, I believe, is one... there are others... Pentosin, Hepu... They'd all be preferred to a so-called "Universal" coolant that has had numerous changes in formulation - none of the details of which are provided the consumer.
As for non-factory parts... you are aware, aren't you, that VW doesn't really manufacture the idlers, water pumps, tensioners, belts, etc. for their cars. If one buys a truly "unknown" part from a less-than-reputable online vendor, he deserves what he gets. If one buys aftermarket parts from known vendors, he's in no worse a situation, and frequently in a better situation than someone who blindly buys from the local dealership. Oh, BTW, I've received quite a number of incorrect parts from various VW dealerships...