First of all, just to be clear. (apologies if you are trying to accomplish something else)
The metadata plugboard is NOT for manipulating filenames or paths sent to the device. For that, each device (while connected) has a 'Configure' option on the Icon. That is where the FILE (path) template is adjusted
BTW My K4 saved settings in the config folder had this line (I peaked under the skirts)
Code:
# use author sort
# Use author sort instead of author
use_author_sort = False
I sorta remember there was a tickbox on the configuration screen, but I don't see it (no device handy)
Also remember that once a device has connected, that used a snapshot of the
Preferences:Plugins entry at that time. Further configurations must be done with the device connected (so you can use the Icons 'Configure')
You also list you have a Kobo and a Kindle.
Those will need individual attention in both places . (There is no OSFA in
device settings
) They all do things differently.
OTOH The plugboard is for
trickery when the device uses internal metadata for management.
Since My K4 has no Series support, I trick the Title to prefix it with {series-index} -{title}