Added an answer with the same as the comment above.
The challenge has a problem when it don't define if the exclusion list by gc.com for travelling/wrong cord caches shall be used or not. It will matte alot a cache physically located in the Czech Republic has its coordinates at the antipode on the other side of the earth. A find on it and another cache near that cache will qualify you with 20 000 km found distance even if you only have logged two caches 161 meter apart
I am also surprised that is was allowed because challenges "One should not have to 'give up' finding other geocaches to achieve a challenge cache's requirements." And the distance from home to N E S W will do that.
example: If your current most E find is fart to the north of your home and a new found is marginally more to the east but on the same N as your home coordinates the distance will decrease.
And you have to give up finds to meat the requirement.
If only Lat distance of N S and long distance of E W is used it would be ok.
A complete checker is impossible without the home coordinates.
The most N E S W caches are independent of home coordinates. At least N and S is and depending of the definition of E and W they might also be.
A checker that shows ok in som cases could be made if the distance between N and S, E and W is used. A min distance will be known but your distance depend on your home coordinates.
