Massive Mod Spawns

Hello,

iw as reading many Forum Posts and also Help Pages of NeoForge.

If i try to use NeoForge example Codes on my MOD to prevent tons of custom mob spawns in warped_forest/soulsand_valley, my game just crashes, so the showed code could be outdated? Of course i set the Spawn weight of the origin mob to 1, i cant set below 1.

I also tried to make entries in biome modifiers, but they dont even affect my custom mob spawn rates, guess because values <1 also dontr work here.
I can´t find any helpful solution to set the chance of mob spawning of my custom one to about 1%

I tried this page: https://docs.neoforged.net/docs/worldgen/biomemodifier/#built-in-biome-modifiers
but only receive game crashes! (yes, i use NeoForge).

Can anyone SHOW UP a working code ? Suggestions dont help. There are many people with this problem (or close) but didnt receive help that worked.

Thanks in advance!