Hi Kneops,
sorry, still can't halp you.
I've spent some time looking at darktable's Lua API to figure out
whether there would be an easy way to solve your problem, but there is
not.
I came up with a *very experimental* Lua script (attached) that can
call `exiv2` to modify metadata in XMP files,
@Hajo, I haven't been able to find the Digikam (XMP) equivalent of the
DT tag list. Do you know which one this is?
Also (this is a Digikam question, sort of) I can't figure out how to use
Digikam to show folders. I can only import/add images to albums.
By the way, I still can't work with this.