To reformulate the question so that I know for sure1 what you are asking:
"Sometimes religious experiences are a result of delusions, so we can't say that such experiences justify religious belief. Even so, might certain religious beliefs be true?"
Obviously, the answer to that is "yes", since there are many things that are true but which we lack justified, true belief. For instance, someone will win a lottery in the near future despite many people believing they will win and none of them being justified. Further there are people who have convinced themselves that they do have justification because they've developed a system or received the numbers in a dream or whatever. At some point, one of those people might win the lottery and turn out to have true belief justified by whatever evidence they suppose they have.2
But you also ask whether religious knowledge can be persuasive based on religious experiences, which is a separate and trickier question. In the lottery case, few people would accept that some knowledge of future lottery results is justified. Even if someone really was justified in believing they knew future lottery numbers (by bribing the person who picks the numbers to somehow manipulate the results or inventing time travel), consider the difficulty involved in persuading someone else they have such knowledge. Only the most gullible would believe such a claim.3 There are just too many cases where something too good to be true is for most of us to take such extraordinary claims at face value no matter what the evidence.
However, I wonder if your assumption that recent research has shown religious experiences to be unreliable holds. Polling data shows that, at least in the US, equal numbers of people report having "Religious and Mystical Experiences" and not having them. Global polls would likely show that most people have had those sorts of experiences. And history suggests that these sorts of experiences are overwhelmingly normal for humans. Extrapolating a bit, they seem least common among populations that have taken an a priori position against the possibility of such experiences. Confirmation bias would suggest that in those populations, evidence for such experiences is ignored and evidence against is highlighted.
Now it's certainly possible that more enlightened populations are justified in dismissing religious experiences, but starting with the position that they are not reliable evidence would be a form of begging the question.
As a Christian, I'm compelled to point out that Jesus didn't seem particularly concerned about convincing people that his claims were true. In fact, he was purposely vague on some points:
And [Jesus] said to them, “To you has been given the secret of the kingdom of God, but for those outside everything is in parables, so that
“they may indeed see but not perceive,
and may indeed hear but not understand,
lest they should turn and be forgiven.”
—Mark 4:11-12 (ESV)
This is a very difficult passage for me, and I'd imagine for many believers. It seems that God gives some people the ability to recognize him and does not give "the secret of the kingdom of God" to others. It seems that God may be hidden in plain sight. Make of that what you will.
This is a restatement of the Gettier problem, if I understand correctly. The main thrust is that a person may have justified, true belief, but not really know something. That does not seem relevant to your question, since you don't actually seem to promote the JTB formula.
I'm reminded of the BBC special in which a woman was convinced that the host (Derren Brown) had a fool-proof system for selecting horses. It turns out the woman was the victim of survivorship bias and that the "System" was a hoax. What strikes me as interesting about the show is that there are people who have the ability to successfully gamble on horse races, but it would be harder to convince skeptics of the ability since it's nowhere near perfect. Rather, the ability has more to do with expert risk management than some mystical ability to know which horses will win.