Calcite sand is cleared with a Cleansing spell. To clarify immediately: any attempt to convert someone in the squad will obviously be considered an aggressive action...
A successful conversion without witnesses doesn't trigger anything. The victim in Ryn will believe it.
But I don't have 20 Faith again. You're afraid of the Dungeon. 8 Faith is a ton of experience. I raised it primarily because 10 is the minimum, and if it drops even by one, a character will die.