Custom spawn weight for modded biome?

Hi I'm having issues with a mod's monster spawn weight, in this 1.18.2 version they do not include their spawn weights in their modded biome and isn't doing well against other modded competition.
I've watched a few videos but can't seem to get it right or know what's entirely needed. Does someone have an example document I can follow? 
this is an example format I have:
{
"starts": [],
"spawners" :{
    "monsters":[
        {
        "type": "mod:mod_mob",
        "weight": 200
        "minCount": 1
        "maxCount": 3
        }
        ],        
    "creatures":[],
    "ambient:[],
    "underground_water_creature":[],
    "water_creature":[],
    "water_ambient":[],
    "misc":[]
}