1. Please ask the app, or discuss elsewhere, for questions about the app. This is not a data problem.
2. Simple, it's exactly because  `denomination=mormon` has been coded with an icon in that app. It has been explained there. https://github.com/organicmaps/organicmaps/issues/4931 https://github.com/organicmaps/organicmaps/pull/5821 https://en.wikipedia.org/wiki/Symbolism_in_the_Church_of_Jesus_Christ_of_Latter-day_Saints#Guidelines