LewdArcana can be obtained while fucking monsters or in dungeons. Lewd Blooms are found in the dungeon or obtained byy fucking with the crystal hearth equipped. Or did you mean something else?
We had to deactivate it in one release, maybe it's this one (I'm not sure since we're 4 version ahead rn). It's reactivated now though. If no slimeling spawns when you hit the big cube, then it's that release.