Did the holy water itself have additional energetic properties and efficacy that made it an indispensable component for the cure? If somebody had, let’s say, opened and accidentally spilled the water, and replaced it with locally sourced water without telling the owner, would it have made ANY difference in effecting the cure?

The water was conveying the blessing that bestowed the holy aspect that is meant by the term "holy water." As such, holy water carries with it the energy of the divine as a conveyance and can deliver healing energy with ingestion or through contact. It is not an idea. It is not a supposition or a placebo effect of the believer thinking something beneficial happened so the body does something mysterious with the expectation of relief and then relief comes. The placebo effect is a garden-variety demonstration of human-level healing capability inherent within the makeup of the body itself. Humans do have healing power and the body has a kind of energetic wisdom it can work with to bring itself back into balance, and there is an interplay between mind and body oftentimes with the expectation of healing to bring those mechanisms to bear to return things to a balanced state and symptoms will ease. Those effects are generally mild and fleeting. When there is a serious illness present, it eventually will override the placebo effect, and this is enhanced when the sufferers themselves see the signs of illness returning or worsening and then lose their confidence that the healing is going to happen. This is the classic behavior of the ephemeral nature of the placebo response. Many substances are embraced as effective because they are new on the scene and the high expectations for their efficacy cause them to have a positive benefit, but eventually when further study shows there is no logical basis for the effectiveness and this knowledge spreads, people will lose confidence in it and the placebo effect will wane accordingly. A divine intervention is quite different because the energy of love bestowed to help the sufferer carries with it the answer to their dilemma. So it is not like a band-aid providing a temporary soothing or protection for a time to shield the problem from being exacerbated, but it will bring a restoration of normality that is always much more profound than a temporary symptomatic relief that is more like a band-aid than a true treatment bringing about a cure. The latter almost never happens in medicine. From the many treatments in current use, almost all are symptomatic in nature and not curative. What will happen if illness resolves, is self-healing, and that can be facilitated by easing the symptoms with medication, but it is actually the body doing the healing and not the chemicals being ingested for a symptomatic benefit. Curing an illness through divine intervention is a profound demonstration of putting the energy of love back into a human dilemma. This is the perfect antidote for human maladies because almost all are the consequence of a karmic trauma in the past, creating an energetic discord that is projected forward through the Law of Karma when it is most appropriate to impinge on the individual and be reckoned with. Those karmic events causing the discord and the energy that eventually wreaks havoc on the body are always an event when love was denied or perverted in some way to cause harm to the self or another, and that is why love is always the answer and the driving force for divine healing. Holy water contains the intention of divine love within. That is bestowed by whoever is blessing the water in the name of the divine, and it is the human intention coupled with a partnering with the Almighty that brings the divine love to bear. And the water serves as a conveyance of divine love on the wings of the human intention requesting the blessing of divine grace in this way, to be imparted to the holy water for this purpose. If an individual’s holy water is surreptitiously substituted with ordinary water and then used with the original expectation of benefit from holy water that lacks the blessing by a priest, for example, there may still be divine healing because the person applying the holy water or ingesting it, or the recipient involved who believes in the divine and believes in the power of holy water to convey the divine healing to them, will serve as the conduit and the supply of human intention allowing a divine intervention to take place. What is missing then is the intention of a priest doing the usual blessing to make ordinary water holy. But a human with strong belief in the divine and a belief in their own worthiness to receive divine assistance can be a powerful self-advocate and, in effect, create their own holy water. Where things will be weakened is if the person finds out there has been a substitute. This may weaken their belief quotient in the exercise and then the divine will not be able to act to anywhere near the same extent, and perhaps not at all if the belief quotient suffers a total loss of faith. This is the one downside of relying on a religious ritual of this kind. What does one do then when holy water is not available? It can become like a crutch and a diminishment of the person who begins to rely more and more on this outside substance than the purity of their own love of God and caring about the self to feel worthy of divine assistance, and have a 100% belief quotient that healing for them will be possible through a simple request in the absence of further ritual. So rituals can be of great value and we will never discourage their use. Anything that helps create positive intention for self-improvement and a partnering with the divine will always have our support and blessings, because this is the normal order and your birthright as divine humans to engage with us and benefit fully from a divine partnership for oneself and for gifting to others through your intention as well.