It turns out you can get Kumiho Cookie from the Lunar New Year Event in Cookie Run Kingdom. What you have to do to get Kumiho Cookie is to never rest the list
See also: Cookie Run Kingdom Guides
Every time you spin the Kumisho Cookie Pouch Mania for 15 lucky pouches, there's a chance you'll get Kumiho Cookie If you use 315 pouches before resetting the list you can clear the entire board which will guarantee you a kumiho cookie.
If you're lucky and you get Kumiho Cookie early on, then you should immediately reset the list so you can have a chance at getting kumiho cookie a second time, which will give you 20 kumiho cookie soulstones.