There is no bug with Crystal Caverns drop list. You can always check the actual drop list on https://l2wiki.com/Kechi#Armed. It uses the same drop script as game server (all drop data is actually taken from game server).
its not a secret that drops are WAY worse then before, i for myself have stopped doing cc , waste of a time
Yesterday made it the 3rd day in a row that we got nothing but Enchant Armor R (and we reset it x3 to get Armed). I don't know about the drop list, but you might want to check it out. We have 4 Prestige Runes as well and we used to get drops with less PR before weekend.