I don't see the need to go looking for a mechanism..
And if we can accept the (acausal?)/ascientific/non-mechanistic/dreamlike reality of the jester incident, ..
As if I, you, or a scientist somewhere will someday discover the mechanism by which such an unlikely event (the apparition, the jester) could have entered one's reality.
So, basically it's ok to be a 'believer' ?
For a moment let us apply this to the, apparently, simpler case of ufo sightings.
If they are real (in the accepted sense of real) than they must come from somewhere. And then, it seems, must also return to the somewhere they come from.
So, it follows that if all attempts by our considerably powerful ranks of scientists can't find a source for them, them it would imply that, A) they don't exist. or B) there is some form of physics we do not understand.
Personally I would opt for B.
There is another option. That it is all in the mind and these things do not exist in objective reality. This is a difficult one to prove one way or the other.
Following the above logic, it would seem that the appearance of objects and people 'out of place ' must also be explainable by them being in some other realm and having the capability, not necessarily engineered by themselves, to appear to us in our realm of existence.
How else could it be ?
Maybe they are existing in some extra set of dimensions. But we have no practical way of showing this regardles of millions of pages of obtuse maths stating it is probably so.
Once you hit quark level everything become rather strange.
If they (Fortenean episodes) happen at all, they must have an origin and a transport mechanism.
INT21.