How are Thought Cloud stats determined?

The Thought Cloud stats are displayed as the Bravery, Truth, Compassion, and Justice diamond. These are the stats used in blade bonding. Check the bottom right of the screenshot below to see it. How are these levels calculated?

I thought it was tied to the number of affinity unlocks your blades have with that symbol, but Dromarch currently has 7 bravery while the other blades equipped on Nia have none (and the game says she has 5). I tried equipping other blades on her with more unlocked bravery affinities, but the stats didn't change, making me think it goes off all the blades the character has. But how exactly are these levels calculated?

I've been trying to find out myself, and I think the best answer we'll get unless someone disassembles the game is "it's complicated."

It seems like the best knowledge we have is there is an XP system, and each affinity node you unlock for a thought cloud trait gives you some XP. Higher-level nodes are worth more "XP". But nobody has gone so far as to deduce the point values or the values needed to level.

But it is true that, eventually, leveling nodes for a particular trait will increase the driver's level. But there's not a way to know how close you are.