We (kingdomservant) have two caches starting with the letter Z. However the checker reports we only have one.
kingdomservant does not fulfill challenge CGCC 027: Spell PUZZLE Challenge (GC5H0ZH) according to https://project-gc.com/Challenges//45707
2015-02-15 Phoenix Totem (GCGH09)
2018-05-15 Unofficial Holidays in 2018 (GC7JKWC)
2016-12-16 Zhecul Cnex (GCT2XG)
2015-07-01 Lincoln-Douglas Square (GC2RRBC)
2015-03-15 Easy Alphabet Challenge (GC41AC8)
But, we also have found 2014-06-12 Zymurgy (GC22ZWZ), so we do qualify.