There's still a lot of implicit lore you can find by reading the descriptions for technologies and unique artifacts in the game, on top of completing faction questlines.

For example: The Drakken are IMPOSSIBLY persuasive. Their unique faction ability is that they can /force/ other factions to truce, peace, alliance, or war (with the sole exception of the Necrophages). While this might not sound powerful if you're familiar with more conventional 4X games like Civ5, changing your status with other factions in Endless Legend costs Political Prestige (on top of having to deal with the diplomacy AI) - so you literally sometimes cannot afford to go to war or make peace. While exploring ruins, you'll also occasionally run into a Drakken scholar who will convince you to randomly go to war with your neighbors. Their own questline is filled with even more of that. I wouldn't be surprised if a Drakken was leading the tribunal.

[@Ezrath], the Vaulters are actually associated with a particular party in Endless Space, so I am told. I've only played Endless Legend, so I wouldn't know all the details, but reading a little into Endless Space Lore might very well also be helpful.