Thank you ever so much. I think I have fixed the UB,but things still does not work entirely since the mod does not show up in the menu. I enabled logging like you suggested, and from what I understand the issue is in the following log:
[3928.359] table Trait_FreePromotionUnitCombats has no column named CombatClass
[3928.359] In Query - insert into Trait_FreePromotionUnitCombats('TraitType', 'CombatClass', 'PromotionType') values (?, ?, ?);
[3928.359] In XMLSerializer while updating table Trait_FreePromotionUnitCombats from file XML/Fluttershy.xml.
So if I understand this right the problem is in the trait. I tried to follow the advice and rewrote the trait, but nothing changed. I now have all three of "('TraitType', 'CombatClass', 'PromotionType')", so I am at a loss for what I am missing here. Values, maybe, but what does that mean, exactly?
Thankful for any and all advice.