Already the conditions you describe violate the conditions of naturally-motivated prayer. Telling someone to recite some incantation does not count as prayer. Prayer is an earnest self-motivated reaching out to God. Similarly, the waters at Lourdes are not some some kind of Harry Potter magic. Those who think they are will likely be disappointed.
Where does the bible claim God is a miracle vending machine?
The evidence, as I said, is the testimony of the martyrs.
I noticed you place quite a lot of emphasis on this point, but I don’t see why this is such an important question to you. What does it matter when ensoulment happens? A developing human is human, not some other animal, before and after ensoulment.