I doubt you would end up with a drawing that would look like the rabbit/duck. You’d probably end up with a clear rabbit or a clear duck, depending on what that person saw. And if you didn’t have prior knowledge of the rabbit/duck, you’d likely not think “oh yeah it could be a rabbit or a duck”, you’d just think they saw different things.
But we all have references for rabbits, ducks, and optical illusions— as well as places, people, etc. A spiritual realm could be something completely out of ordinary experience, for which we do not have adequate descriptors. So people settle for analogies and similes (eg “it was like this”), which will necessarily be colored by their culture and experiences. To add to the confusion, we know about religions so we may automatically place a spiritual experience within the context of a religion with which we are familiar.
Sure, it would go a long way to verifying these spiritual experiences if they matched. But the fact that they don’t match, doesn’t rule out the possibility that they are the same thing.
(And, honestly, many religions/spiritual experiences do tend to have similar aspects even if the entirety is divergent.)