If I add entities myself! It doesn’t make them follow the rules i set they simply follow the global mob grifing rule false (yes I tested it in a new world and using the command actually works).
Here is an example of what I added
S:iceandfire:firedragon=true
S:iceandfire:icedragon=true
S:twilightforest:naga=true
Also it automatically turns them into this in the confige file when starting the game
S:firedragon=true
S:icedragon=true
S:naga=true (I have like 3 different nagas if the config deletes the “twlilightforest: “ before the naga how does it know what naga is meant??)
They do appear in the in game config but changing the value doesn’t change anything.

Here is what the config looks like now https://pastebin.com/YMiMhQa9 after booting the game when I added the things. It auto removed the modprefixes and sorted them alphabetically.
They all had their own “# [valid values: [true, false, inherit]] [default: inherit]” above them when I edited the config.
Well anyway adding moded mobs to the configs to automatically have them set with gamerules doesn’t work.

This mod just uses the inbuilt forge config handling, which I suspect doesn't support colons in the property key. I'll take a look when I get chance and see if there are any alternative ways to achieve what you're doing.

the command works fine so what i crrently did is have a hidden command quest autocompleat and executing a list of commands setting the mob ´s i want to true.........just adding mobs to the config doesnt work.