Only Npc Kills easy when player reach npc kill

Hi, thank you for your plugin, very usefull and it's bringing a good gameplay for players !

I'm just facing a problem, indeed when the players kill a certain amount of scientists (around 50) the event about npc kill is ALWAYS on easy, i would like to change that, i've tried many times on config file to change that and nothing change.
Where i'm wrong ?

Post your config

RandomRaids.json