Lastwall has a policy of writing an incident report whenever the Goddess directly intervenes in some way more unusual than empowering a cleric or paladin (and sometimes even then, depending on the circumstances), in case they could have, with better policies or better practices, spared her the expense. They can't always perfectly implement this policy; if the Goddess sends a vision to a knight of Lastwall, Lastwall will certainly hear about it if the knight survives the circumstances that precipitated the vision, but Mendev is... worse... at communicating with people about things like this.

Mendev could not hide the Miracle of Kenabres if they tried. Most of Lastwall's agents in Kenabres did not survive the aftermath of Deskari's attack, but one of them manages to report everything she knows about the incident over a Scry. She personally witnessed a blinding flash of light above the Grey Garrison; allegedly, Iomedae directly intervened in some fashion to save the Wardstone and/or defeat a powerful demon, though rumors disagree as to what, specifically, the intervention involved. The general consensus seems to agree that it involved a vision delivered directly to a Calistrian priestess. Somewhat more is known about the priestess and her companions at the time, who include a paladin of Iomedae, a tiefling thief, a... tiefling? technically-not-a-tiefling?... who was supposedly recently chosen as a priest of Iomedae, an elf child, and a wizard. No, this agent does not have a good explanation for why, if it was actually Iomedae who sent the vision, she sent it to the Calistrian priestess rather than either of the Iomedaeans.

(This is sufficiently surprising, and the surrounding circumstances in Kenabres sufficiently dangerous, that Lastwall determines it to be worth spending an emergency Commune to confirm it actually occurred.)