If you spelled his name correctly, I think ‘thekoreanpanda’ doesn’t have an account on the forum (the @thekoreanpanda doesn’t turn into a link as for other accounts). You might send a message to Lien (top-right profile icon, then the envelop) to ask if she can make you a contributor or can contact the creator for you. Happy learning!
Apologies for my slowness (since having left Support nearly 2 years ago to focus on internal office operations, I sometimes struggle to keep up with the forum).
The Korean Panda hasn’t been active for a long time, they’re an endangered species after all
As a sudden comeback seems unlikely, I have added you as a contributor. Via the ‘Edit Course’ button, you should now be able to add those missing chapters. More info here