I really should not fire off wordy posts early in the morning, especially after I've woken up a couple hours too early and/or am angry that one of my tools isn't working. I've deleted that post, so here's some highlights -
A line I chose to omit from the end end before posting - "It'll be funny if, after typing all of this, I get the script working by noon." ...it is now just after noon, and I got the script working 15 minutes ago.
The kicker to all of this trouble? I'd already solved it last year when I was rigging Violet. I had documented every step needed to fix the rig, but I just never bothered to apply those notes to the script. If I'd bothered to consult those notes sooner, I might not have had as much trouble with this thing.