The society of an island nation is led by a religion known as "The Church of the Eternal Mother", it is an ancient faith that adheres to a fertility goddess. This faith is led by five elderly women called Mannas Natau, at least one of whom will regularly become spontaneously pregnant. These immortal elders are worshipped as avatars of the Eternal Mother: mortal vessels of the goddess's power responsible for creating life and growing the numbers of the community. Children born from the goddess are biotically immune to all illnesses and live longer than other humans, but are not immortal. The goal of the community is to ultimately build an empire by conquering its neighbors.
Although the elders have the ability to immaculately conceive, the vast majority of children produced, about 90%, are stillborn. This has prevented the community from growing their numbers rapidly and to a large extent, even after thousands of years. As this would put a kink in the eventual goals of the nation, it would be natural for people to become disenchanted with their leaders. With a god that is metaphysical and unknowable, it would be easy to rationalize negative outcomes and bad events. People can dismiss these occurrences as "God works in mysterious ways", or that he doesn't interfere in the lives of mortals directly. However, these elders are considered the Eternal Mother made of flesh and are thus living gods. Their failures are actively seen in real time, making them difficult to ignore. It would be like Jesus trying to perform miracles and failing, or having them have negative results (Lazurus coming back as a zombie and eating people, three loaves of bread and two fish multiplying but turning poisonous, etc.). Such outcomes would damage the credibility of those claiming to have a special connection with some deity. Loyalty would be diminished, turning their followers against them at some point.
How can the church maintain its influence among the community despite its repeated and visible failures?