I've got fatigue and am frustrated to read English sentences here, I know people have expressed their meanings well but just quite a bit difficult for me a non-English-tongue to comprehend, my bad of course ;)
One thing about false-memories or deception, which confuses me, is that speaking to me, I never had any false-memories (but had obscure memories which I clearly knew they were obscure and shouldn't be relied on), and I seldom took interested in confabulating loads of unreal tosh or balderdash just to fool the others.
For example, if I am asked my memories about a past event which involved me, I would describe something which I don't clearly remember as "I don't clearly remember", I would describe something which I clearly remember as "I clearly remember that thing" followed by almost meticulously detailful narrating about that thing, and later all can be proven correct.
I know precisely whether my memories about a certain event are clear or obscure, are "absolutely real" or "possibly wrongly", are dream-like or practically real, if I feel clear, then the fact always is that my memories are actually clear and conform to the truth, in this kind of situation I always report correctly about the facts of that event, on the other hand, if I feel my memories are at least a bit obscure, I would say: "If I don't remember wrongly, that thing would have been such such, but I might remember wrongly so it could also have happened in the either way."
Take an example, one day I went to work, and when I was working in the company my daddy phoned me and asked whether I had shut every lamp in our house, I did check the whole house before I left but since I got up late that day morning and was in a hurry I didn't check very very focusingly so I would had answered: "Sorry daddy probably all shut but I didn't remember very clearly".
And the next morning I got up early, and after had gotten ready to leave for work, I checked every lamp in our house, in an order of from "the farthest to the door" to "the nearest to the door", my parents' bedroom: three lamps, shut; kitchen: one lamp, shut; washing room: two lamps, shut; my bedroom: two lamps, shut, parlor: one lamp, shut, etcetera, so later if my daddy would ask the same question, I would clearly know my memories are NOT obscure and simultaneously NOT incorrect.
Maybe it is not as crystally strict as I claimed above, maybe they need to be quantified and don't reach 100%, but to say someone asserts that he clearly knows his experiences are real, but at the same time he actually really doesn't quite sure about their reality, and he can't verify or prove even merely to just himself that those experiences are real, this psychology is unimaginable to me, just like religionists saying they clearly know their gods are true gods, is also contradict to me. Maybe because I'm very practical a man and someone else may not be that practical, which I couldn't vicariously imagine but I could try to fathom.
As to ndes and many relevant claims, whether they are veridical to the nders themselves, veridical to the truth behind the phenomena, veridical to the others, or deception to the others, or self-deception to nders themselves, or deception to the truth behind the phenomena, or a combination of some of these, all can't be concluded currently.