Yeah that's probably a mod conflict. I tested extensively to make sure the unique trait was working. What mods do you have enabled and what Unit did you kill?

" Destroying enemy Units whose prerequisite Technologies have not yet been discovered by the Outcasts will grant them bonus Science towards discovering that Technology, equal to roughly 25% of that Technology's total Science cost. '

What I got was 1 ONE point added to every remaining tech to be researched. Not all added to a specific tech. I suppose it could be a mod conflict?