So, yesterday I pinged both Mixam and Artiforge about progress. Today I received my answers, in two ways.
First, I heard from Artiforge, the card vendor. They told me that the cards were printed and cut (wow!), and were being bagged as we speak. Probably done today, but given snowpocalypse 2 might happen again here tonight, they recommended a Friday pickup.
That's excellent.
Hand-bagging the card decks at Artiforge.
I also sent a note to Mixam for an update. They said they'd check with production and get back to me.
Imagine my surprise then when my Arlo video doorbell said "package detected" and I found fresh copies of Serpents of Legend on my porch, with all 60 pages this time!
Serpents of Legend! With proper pages! And the Snake-Bear!
So: final fulfillment begins this weekend. I shall aim to get everything in the mail Monday morning, I hope. There really aren't that many packages to get going.
I will also hope to hear back from GamesQuest UK about sending over the fewer-than-20 decks of cards and anything else I'm missing for the UK-hub orders.