So, wrapping things up, I've called the companions the TerraGuardians, and made them have kind of the same AI as the NPPlayers from N Terraria mod, but better. For them I had to literally create a new kind of entity on Terraria, so they're not npcs or projectiles (like the summons). Alongside that, they have a friendship level system, where rising it's relation with your character allows them to do more things for you.
I forgot to tell you, but I've released the mod about last week, and based on the initial reception of the mod, which has been kind of good in my opnion, I guess I should try to improve it more, I see good potential on it.
In case you want to check out the mod, here's It's page on Terraria Community Forums:
https://forums.terraria.org/index.php?threads/terraguardians-terrarian-companions.81757/
As for TNR Project, I may resume the development of it on the next week, so I can work on changing the skill system.