If i don't misunderstand i you shall have found all caches from a CO. Only active and non premium non events count ans the CO shall have 100 to 149 active caches
That is possible to do a checker for but the requirement that the CO has been on the website in the last month are not possible,i could be "faked" with a log the last two months
And you cant check if you have use the same CO on a different one in the series. This is the big problem because it can generate a lot of false logs when a CO places a new cache and you log it and the checker thinks you are qualified for another challenge