Well I completed all the CGs also. Mandilitrio is the hardest, like much harder than the boar NPC. Boar NPC - need to find all mines, Mandilitrio, need to befriend and talk with every NPC with the statue (Its also locked behind the cat quest and the mushroom quest and need to give 2 special NPCs special items)
you need to do the cat quest
It's given by one of the NPCs who gave the potion. The reward is a tea voucher to exchange with a potion
To get the scene they said
1) give the special items to the artisan
2) give the special mushroom to madeitto (it can be found in his cave. What I did is to climb up and for the NW part since that is when it's hidden
3) THE hardest (need to show the statue to every NPC)