Having exhausted all identifiable options for adding new content to Chordie and getting no response from numerous emails to support I've developed a work around for adding new content.
Just find a song with a title close to what you want to add, add it to your songbook, and then completely replace the content. When you edit the artist and title in the song it won't change how it's displayed in the songbook so you'll have to remember what it is really. You can update the content of the song for tab, lyrics and chords as needs be. I'm finding this to work quite well.