I'll probably have people coming at me with objections for this because we're in the business of misunderstanding each other here, but this is true in as much as I can tell and it is true that the workings of Delta are not in my comfort zone. Te/Ti, Fe/Fi recognition and distinction for Betas NFs comes from continuous chafing experience with Delta STs. Fe and Ni builds such a predisposition that the psychological primordial stew of Fe/Ni NFs but quite markedly of LSIs also is a constant, timeless replay, with variations and adaptations, of this:
It's not for no reason that the questionnaire to get typed by Gulenko makes a point of asking about daydreaming. As said predisposition exists interaction with Delta STs becomes a meeting of the fairy-tale minded fools with, from their perspective, petty, ignoble, selfish Delta STs. Nobility, under any other notation, is big for Betas. It's there when they're children and no matter experiences and bruises during their lives, they never grow out of it, leaving them totally defenseless against “the real ways of the world”. That's Fe/Ni for Beta NFs: impossibility to close off ‘others’, to just live minding their own business and aptly securing their interests, thus they're the gullible, too trusting in everyday life (Deltas will probably have another take on that). To determine your type you'll have to be honest about what's brewing within: Betas NFs are anxious about everything that undermines their Fe collective and fantasies and ideals will be a projection of evil that always threatens to rear its head to attack their weak point, with a dual as equally pure as them but dexterous in ways they're not that appears when times have never seemed darker. Delta NFs being oriented at the business logic and ‘individuality’ of Fi would have a different type of fantasy world.