@Polemarchos
No new rosters. It simply takes the existing rosters for the Normaunds, Dene, and Norse end-game invasions and 1) changes the faction flag, 2) changes the faction name, 3) changes faction colour, and 4) changes theiir in-battle unit colour.
And there is a mod where you can play as emergent factions in custom battle. However, for some reason when testing this mod weeks back, once I changed the Dene faction colours, they wouldn't show up in custom battle. You can check if that's changed but if not, then idk how to fix that.

Does this mode include new rosters for new factions? If so, can we check it on custom battle?

Maybe you have another mod conflicting with it? When I made the mod, I tested it on a Legendary Wessex campaign (this was before I made my all 3 invasions for all difficulties mod) and it worked just fine. I even just now re-uploaded the saves from my Easy Wessex campaign (from when testing the 3 invasions mod) and I activated this mod; it still works fine.

i have done the same Bro) I have highered up in the load order, but doesnt work

@timurkebekov
It works for me just fine. Maybe it needs to be higher up in the load order?

I did notice though when checking that for some reason the version I uploaded didn't have the in-battle uniform colour changes, so I fixed that and updated the mod.

it doesnt work bro (((