https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2937742808
use mods. they are absolutely needed for this game

I found the modifiers. They are located in lua_scripts folder in politics_trait_defs.lua.

--polit_trait_common_difficulty_level
--#####################################################
polit_trait_common_difficulty_level = {
is_common = true,
evaluate = function(faction, party_id)
local loyalty_mod_per_difficulty = {
10, -- easy (1)
0, -- normal (0)
-10, -- hard (-1)
-25, -- very hard (-2)
-25, -- legendary (-3)
}
return loyalty_mod_per_difficulty[2 - faction:difficulty_level()] or 0
end,
},

Changing their values did work in campaign. Instead of just totally removing civil war like most mods in the workshop, or altering party loyalty to stupid high numbers, messing around with these values will probably be way less intrusive on the game, if you still want the civil war mechanic, which I do.