"If the question was 'Will the ritual be performed? 'my answer would be
that it would very probably not be, the conjunction of the Moon with
Venus would prohibit it."
How does this work? why would conjunction of Moon with Venus prohibit (or tend against) the actual performance? I would have read a conjunction of Moon and Venus as affirmation rather than negation. (not that I know Horary)
In this horary the Moon is Lord 1 and significator of the querent. The normal considerations regarding the Moon would not be enforced, so it being in the Via Combusta (which I don't use) says something about you, not whether the chart is valid. Ideally we would want the Moon to be applying to and perfecting the sextile with Mercury as its next aspect and Venus placed in a lower degree but still conjunct. However the Moon's next aspect is actually Venus. That conjunction prevents or prohibits the matter as the Moon process stops when the significator makes it's next aspect, unless it can translate its light to another planet that will go on to aspect the other significator as it's next aspect. So having taken the light from the Moon, if Venus went on and aspected Mercury as its next aspect the matter would still be perfected.
However Translation requires either a faster moving planet to carry on the process (well one that's faster than the other significator - either Sun or Mercury depending on which house system is being used). Alternatively a very slow planet would do, such that the other significator catches up with it and takes the light, of the Moon.
So if the Moon were to aspect Saturn as it's next aspect and then Mercury or Sun (whichever is Lord 3) aspected Saturn as their next aspect, then the matter would be perfected.
But the Moon will aspect Venus next:
If Mercury is Lord 3 Venus is so far behind Mercury in degree and is also slower than Mercury, Venus can't catch up before Mercury changes signs and even then she will continue to fall behind.
If Sun is Lord 3 Venus cannot achieve any aspect with the Sun except for a conjunction. That could only occur from the present positions if Venus turned retrograde. Pretty quickly. In fact Venus will not turn Retrograde till March next year.
So there's not a meeting between significators, so no action to perfect the matter. That would hold, even if your friend did use Neptune. Currently it's Retrograde in Pisces and at the time of the horary was in 9 degrees 50 minutes approx. So Moon and Neptune are separating, not applying at the time of the horary. As Neptune is retrograde for long periods of time and also very slow, Venus will be long gone by the time Neptune turns Direct.
So 'Will the ritual be successful?' It looks powerful in both charts but neither chart promises perfection of the act of performance. As you have control over your own actions you can override the chart and perform the action, in which case the outcome looks good, from both charts.
Horary doesn't compel people to perform. If the question is 'Will she marry me?' this doesn't mean that with a chart which says 'Yes' all you need do is sit back in your chair and wait for her to come knocking on your door. Nor does it mean that if you don't answer the door, she will break in to get to you.
You have to take the necessary steps to win the girl or to carry out the ritual. So at the time of the horary, were you unsure that you were going to perform the ritual, or even looking on the election chart as more of an
academic exercise. If you were, then the chart is actually right for that moment in time, and it might be the subsequent discussion that gets you fired up to perform the act at the desired time.