If I understand correctly, the metadata plugboard is for making templates of existing fields that overwrite a destination field when sending a specified format to a specified device. I added a plugboard (for any format and any device) that sets {title} to Title lol. However, that did not help.
One of the files giving me trouble:
https://www.gutenberg.org/ebooks/61436.kindle.noimages . I want to change the title from
"Ancient legends, Mystic Charms & Superstitions of Ireland / With sketches of the Irish past" to
"Ancient Legends, Mystic Charms, and Superstitions of Ireland, With Sketches of the Irish Past" on my Kindle.