Concerning the golden idol, AFAIR it's just randomly determined. Sometimes, some monsters/characters drop specific items when you fight and win against them, but I don't remember any with such a kind of loot.Is the "Reducto" quest still broken? I cant unlock the recipe in the study in the evening. Can revert back with cheat room but that doesn't complete the quest.
Also is there somewhere specific i need to go for the gold idol? Been doing dungeons with Eric for in game days and it hasn't shown up.
So, I guess the only solution is to try and try again.
See this post (it was about another item, but the method is exactly the same): https://f95zone.to/threads/warlock-and-boobs-v0-339-1-boobsgames.18692/post-5424233
BTW, there are about 27 or 28 possible items: that gives you the basic chance to get a given item each time ~ 4 % (though it's possible there are some additional conditions for some of them).