What I did (I think this is essentially what you suggested):
I booted to a backup volume and ran DiskWarrior 5.0. My main volume’s Optimization Index was “10”, so I was not hopeful that continuing with the repair would be beneficial. But I did it anyway.
The result was that “60 Files had a directory entry with an incorrect text encoding value that was repaired.” All 60 files looked like this (but with differences in the file numbers):
File: "ヒラギノ明朝 ProN W3.ttc_ATS_692_266870060
"
Repaired Text Encoding
Location: "Zeus/private/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/T/TemporaryItems/"
After allowing the repair, the -43 error issue was resolved.
FWIW: I have used DW for many years, but always it was as a preventative measure. AFAIK, this is the first time it resolved a problem after the fact.
Thanks for the Recovery Mode tip; a very good thing to keep in mind and I hadn't even considered it.