A staple of RPGs, hell, good game design is that if you're not sure of something in game, there is someway to discover it, be it through discovered lore or NPC dialogue. It's not good game design to just put something in the game and leave it up to the players to try all sorts of random combinations to discover. Of course the problem with Escha is we have a zone devoid of NPCs so NPC dialogue giving away pop item info is a non-starter.
Unless there are certain conditions that reveal what you need to pop the Ark Angels but it shouldn't be a load of guesswork, there is no challenge in that it's just frustration.