Sahra Nguyen couldn’t understand two things about robusta coffee: why it got such a bad rep, and why it was so difficult to find in the cafés she visited in Brooklyn. Nguyen, 36, who is a first-generation Vietnamese American and a filmmaker, began to wonder whether there was something she could do to help rebrand the beans, which are ultra-caffeinated but commonly more bitter than arabica beans. She also knew those efforts could give a boost to robusta farms, located primarily in Africa, Brazil, Indonesia, India, and Vietnam.