Question

"​in which culture would people be held responsible for their dream actions? (for example, an erotic dream about someone could be seen as an adulterous act.)"

Answer 1

That would be the Arapesh tribe.
Arapesh tribe is a tribe of people who originated and live in the Papua New Guinea. According to their culture people are held responsible for what they dream. In Psychology: Themes and Variations, Briefer Version by Wayne Weiten he gives the example of having an erotic dream about a certain person that is viewed as the adulterous act