Your leaders level is not only dependent on what other's think of them, but also on their skill set. Additionally, it's also important to note that if the leader is passionate in their work, this will give a big boost the level.

Example - Warrior score is calculated as follows:

Major Passion = 1.5
Minor Passion = 1.25

A = SkillLevel(Melee) * PassionLevel(Melee)
B = (The same thing but for shooting)

Warrior Score = ( A + B ) / 2

Each leader type has their score calculated differently.

I's thinking it'd be pretty cool to have co-leaders, King Arthur's round-table style for a possible expansion sometime in the future.

The mod's pretty cool as is, I'm just naming a possible future project for a (much) later time.