I used a mod that allows me to up relations and even in green they still aggro. I don't thank you can so you will still need to kill or capture their leader

You basically need to kill the chieftan/leader to unlock the ability to craft Mandalorian armor since it's on them. Personally, Nyhmon lore-wise in this mod are Dar'manda and honorless. So you are not really doing anything bad fighting a breakaway clan that fled to the Unknown Regions to exploit the unstable lands of Kathun. There is an Mandalorian Exile you can find at a uncommon chance in bars to recruit, claiming he was outcasted because he was "weak", which might be true but there is likely other factors at play there considering they are hostile bandits. Wanted posters also speak ill of them as well.

They have a pretty heavy bounty on them and it's honestly just better if you wipe them out to use their armor for money/materials when melted down to make your own. They are not worthy of their beskar'gam apparently.

Shogun_Sorrow is legit

I dig your patch! Very thankful for patience, you inspired me to tweak stuff, i'm trying to release some stuff i did for myself too, once i get it polished - is still too haphazardly put together