All secret levels are in those levels listed in the code. Took me a while to find out. So that means some levels lead to two secrets. With this small hint you will probably get 1009 coins and then I’ll spoil it for you :P
Getting two more coins should allow you to jump up to the platform in the air and get you to the secret x level. It has a coded message leading to every secret level there is.
 "Knaifhogg"){kind=small}