Even though Emperator Fyron answered this question in other thread I can not miss the oportunity ro raise my point count
You can do whatever you like with most characteristics without any detrimetal effects on AI. The exeptions are "racial" traits - Organic, Crystalline, Psychic, Temporal and Religious. Another touchy trait is Natural Merchants. If the race is using it, do not remove unless you fix AI_facility_construction.txt file. Adding this trait to a race will not give it any benefits either till you adjust the AI file accordingly. Also be carefull if you want to change race home planet type. AI_research.txt may need few changes.