While looking in Gameplay Data, I found a file called "Personas".

It contains things, which are basically, like this:

<Name>Airhead</Name>
<Description>AirheadDescription</Description>
<Trait1>Childish</Trait1>
<Trait2>Excitable</Trait2>
<Trait3>Flirty</Trait3>
<Trait4>AbsentMinded</Trait4>
<Trait5>OverEmotional</Trait5>
<IconFilename>cas_personas_i_airhead_r2</IconFilename>

There are others than just Airhead, such as Emo, Goody Two-Shoes and Villian.

I was wondering if these were used anywhere?

Many of the traits were merged with other ones or removed from the game entirely. I think "Goody Two Shoes" became "Good" and "Villain" became "Evil." "Airhead" is probably "Absent-Minded" and "Emo" is probably "Dramatic" or "Excitable."

There's a thread about this here. It does work as a nice reference if one wants something like the personalities listed, or is out of ideas for trait combos.