I don’t think so. You’re asking a particular question – how do we determine whether this apparition has physical effects that are measurable? – but I was trying to ask a general question about the “interface”, which would speak to any action by spiritual forces in the world.
So… let’s look at your case in particular, without derailing the general question:
In the case of a mirage, what’s happening is that our senses are working just fine – it’s that our brain is misinterpreting what inputs our senses are providing.
The example I gave, with respect to apparitions, is that it’s akin to a mirage (it’s not exactly the same): the assertion is that a spiritual being (God, as it were) is changing not the physical world, but our senses or our interpretation of them. It really is happening, from our perspective, even if there is no physical change that is measurable. And, of course, I’m not asserting that this is the only way an apparition can appear.
Perhaps it has, and perhaps it hasn’t.
It’s happened before – this isn’t a singleton event. Lourdes, Fatima, Mexico City – many times.
Are we even talking about the same event? Everything you assert here, I see contradicted in the reports I’m reading. For example, see this article, which makes very different claims about why there’s no official Vatican response, and very different reactions from Church sources…