While I love the intent here, they don't stack. One can only be used when sharing a tile, and the other requires consent.
Also, if I remember correctly, Illusionary Charisma mentions "any 1 treasure card", whereas most abilities refer to "treasure or artifact cards" when artifacts can be affected too. As written, Emma couldn't have convinced the other player to give her the Summoning Stone with Illusionary Charisma.
Maybe you should have won this game after all