TLDR summary is near the bottom.
I've been thinking about this the past couple of days. When typing a person, some people claim to see Delta Ne in the person's writings, others claim there's not enough Delta Ne demonstrated to draw the conclusion of Delta Ne ego. Which brings the question of "What demonstrates Delta's version of Ne?"
Ne is often described as intuition of possibiities. Ne ego types are said to recognize possibilities, create new opportunities, new beginnings, reconcile different perspectives and povs, rapidly generate ideas, etc.
I'm going to focus specifically on Delta's version of Ne...this is the idea of diverging possibilities, of alternate possibles. (Delta's Ne is negativistic/divergent with Fi//Te as the converging factors. Alpha's Ne is positivistic/convergent with Ti/Fe as the diverging factors.)
A helpful metaphor is to see Delta Ne as aware of, and consideration of, "other worlds", "alternate universes". The idea that given a circumstance, there are multiple possible meanings for it, multiple possible developments of it, and/or multiple possible influences on it. Always in the back of the Delta Ne ego's mind is 'possible alternatives'.
This awareness of possible alternatives makes it difficult for Delta Ne to feel complete certainty, to see things in pure back and white, this way or that way with no shades of gray. One way of noticing this is that they seem to hedge their statements with words like could, may, might, usually, often, sometimes, some, seem to, etc. This acknowledges that there are times when what they are saying might not apply.
Delta Ne ego types also often switch between alternate perspectives, alternative points of views. On the one hand, but on the other. This is often seen when they take into consideration the reader's pov, or the opposing side's pov, or other ways of looking at what they are saying. They instinctively know that what they are saying could be read/interpreted in different ways, and so will try to redirect some of those differing interpretations towards what they intended.
Another way that it is seen is when they analyze a situation/person/idea/etc by looking at it from differing perspectives. It's by seeing from these alternative perspectives that Delta Ne ego types are able to start narrowing down the essence of who/what is being studied/analyzed. But still, even as Delta Ne ego narrows down to the essence, there's still the underlying idea that there might be cases in which an alternative is true.
Admittedly EII won't be as extensive in it as IEE's 4D base Ne. But it'll still be there, underlying their thoughts and writings. And when it is not there, it can rub wrong a Delta NF.
TLDR In summary:
So, how to tell if someone is possibly demonstrating Delta Ne?
Do their conceptualizations include differing points of view on the topic?
Do they approach the topic in differing ways?
Do they demonstrate awareness and allowance of alternative interpretations/explainations/values?
Do they allow for cases in which what they are saying may not be true?
Do they fairly regularly use 'hedging' words? (may be, might, could be, usually, often, sometimes, some, seems to, etc)