Not speaking for Australia, but in my state in the US, the testimony of one witness testifying that the accused committed all the elements of the charged crime even without other corroborating evidence is always sufficient to support a guilty verdict (unless the witness is an alleged co-conspirator). The decision to convict the defendant based on such testimony is left to the jury’s assessment of the witness’s credibility. Whether to bring charges in such an instance will rest with the prosecutor. Testimony is direct evidence. “Concrete evidence” isn’t a legal standard. Here you have more than just the accuser’s testimony. You have another witness who the accuser told previously. You have testimony about the church grounds and timing of services. That circumstantial evidence supported the direct evidence of the crime from the accuser’s testimony.