I don’t know what the triumph point value is.
If you look in the Trait files, there are certain trait conditions that have "Triumph Points" as a condition. I believe that this is a point system the game uses to give certain traits (like the "Victor" trait). Conquering Wonders, Destroying Factions, and Conquering cities gives you these points. If it works has it's supposed to, I believe the "Triumph Points" labeled for each city is how many of those points your general gets for conquering it.

If you'd like, I could test it out.