Okay. I've been decompiling some of the DM maps in this game with bspsrc, and I haven't seen any entities for this specific game. I discovered a folder called "mapadd", and there were some text files in the folder, so I opened them with notepad++. I discovered that the text files tell the game to add in specific entites to the map, like npc_maker_firefight (item_lightrmor), which obviously spawns in NPCs (which is the light armor). If any dev is reading this, please add these entities to the game's .fgd file! It would be a lot easier to make maps that way.

EDIT: I've looked at the game's .fgd, and by typing in npc_maker_firefight, it does get me the proper entity. Looking at a mapadd .txt for a map pointed to these entities: item_lightarmor and item_heavyarmor, which show as "obsolete" in Hammer.

Crossed off text about npc_maker_firefight, which shows up in Hammer. "Replaced" that text so it refers to item_lightarmor and item_heavyarmor.