Oh, I didn't see that I put it in the modifier block. Thank you 
Or should I divide it into a changed 00_species_traits.txt + 01_species_traits.txt with my added traits?
The problem with that is (if it even is one ^^) that I want the vanilla leader age traits to exclude my own, additional leader age traits. Is that still possible with 01_species_traits.txt?Also, since you are adding new traits, not changing value assignments, etc. on existing ones, probably best to do it this way:
C:\Users\Anthropoid\Documents\Paradox Interactive\Stellaris\mod\anthropoid\common\traits\01_species_traits.txt
where the file contains ONLY the things you've added.
NOT like this:
C:\Users\Anthropoid\Documents\Paradox Interactive\Stellaris\mod\anthropoid\common\traits\00_species_traits.txt
where the file contains the vanilla script as well as what you've added.
Latter may suffer compatibility down the road.
Or should I divide it into a changed 00_species_traits.txt + 01_species_traits.txt with my added traits?