Well, based on the tracking info posted by the launch day group, it looks like it can indeed be delivered a mere 2 days after the departure scan from ZhengZhou..
This image is from someone elses post:
Bear in mind that it's hard to be certain what timezone these scans are in, but - yeah.
It's hard to say, the departure scan coming in now could even mean the plane has already left. It's not as if they're scanning every one of these boxes. The packages are in an air shipping container, and someone's scanning a manifest. You won't see a scan on the actual box until Louisville when the container is unloaded and the individual contents are routed.
So, for the above already-completed delivery - This flight would almost line up, but the arriaval/departure from anchorage doesn't seem right. But the initial departure from ZhengZhou and the final arrival in Louisville are right within the envelope.
https://flightaware.com/live/flight/CKS817/history/20190918/1500Z/PANC/KSDF
So - what we can be sure of is that we can take the times on the UPS site with a grain of salt.
Now, in terms of those two Cargolux flights - That's an interesting thing going on there. Two scheduled flights leaving the origin, with the same flight number, almost the same time, one has double the flight time?
I sure wouldn't be surprised if one of those was a chartered aircraft continuing on to Louisville (or maybe chicago) after Anchorage, that the flight tracking sites don't have the updated flight plan for - or they're relying on the standard route of the flight number. Or maybe one's direct to chicago - who knows, I'll try to find a flight plan - but - Two flights with the same number airborne at one time? That's anomalous to be sure. (in fact they'll probably have to change one so ATC can disambiguate clearances, but I digress).
Thursday seems like a good bet at this point, IMHO.