Thank you for your answer, I needed to rename them, because when i want to add player-made dungeons, they have their own .schematic, but i can live without them, and yes, the .prop files are text-based
(example of editing the lootpool:
iron = minecraft:iron_ingot,7,0,85
gold = minecraft:gold_ingot,7,0,45
diamond = minecraft:diamond,5,0,15
)