Playing any Wood Elves faction in singleplayer gives you control of the "World Tree" in the center of Athel Loren. If you upgrade this to Tier2, you receive "confederation quests" for the minor WE factions there.

And there are more confederation quests for all other WE factions in the world, like when researching the tech that gives vision over all trees, upgrading Athel Loren to T3, etc.



Well, the quest for the Bowmen of Oreon requires you to win 1 battle against the faction.
Winning the battle gives you an instant dilemma, either confederate the faction or get some diplo bonus.

So the bug happens when you hit "subjugate" after winning the battle against their capital. This makes them your vassal, then you get the quest dilemma wether to confederate.

And now your mod comes in: When using the Subjugate option on a confederatable faction, your mod asks if the player maybe wants to confederate instead. This plays after the original quest dilemma from the WE confederation quest, and when accepting the choice from your mod, the game locks up.