Did you search the exact name, 512: Konosuba 3? This game's search function isn't good. I don't know for sure, but I think the item database file is mostly empty since it's stored locally, the Steam release is quite new, and maybe it gets populated by looking at the Scratch Prize List or other players with it, and definitely when viewing it in shops. I just tried searching on the Steam version with part of the name via the item name search on the side, also didn't show up (likely missing in database file), but putting in the full name and doing a full "Search by Price" brought up the results. Afterward, doing a partial item name search brings up that as the result (likely because it was added to the database when viewed in the shop), but not any of the other Konosuba emotes. So the database seems item by item, no matter how similar the names are. So it's not really a bug just poorly designed. It's the same in JP and has been so for years, but really they should improve this search function, it needs it.