Can't publish - Failed to submit new workshop item (9)
Having read similar threads on the topic, I understood that this error occurs when there is a missing file. In an attempt to solve the problem, I copied all the game / content files from barbones into my mod's respective game / content directories. I made sure not to overwrite my existing files in the copy process. This did not solve the problem and at this point I am left clueless as to what could be the cause.
My content and game directories can be browsed here. I have truncated the content of some files but will upload the original source if need be. If the files need to be viewed I can try to upload them on github (though the last time I tried to do so I got an error). Note they can be viewed in the link I provided but its more cumbersome.