ORIGINAL: vengen
If you have time, you might want to check your character files. At least some of them have characters with inappropriate skill types.
As an example: the first ambassador in the Xflinta file, Ne' lis 'Ehe ros, has skill types 1, 13, 9, and 5. Skill type 1 (Diplomacy), is appropriate for ambassadors; but skill types 13 (Facility Construction Speed), 9 (Troop Recruitment Rate), and 5 (Colony Corruption Reduction) are not appropriate for Ambassadors.
The leaders in the file seem fine, but every other character type seems to have these issues.
I know the Xflinta, Vlomert, Vik'yd and Enton character files have these issues - I didn't check any other race's character files.
Overall, this is an excellent mod, so I'm not surprised it has 1400 downloads.
I've noticed this issue. I think when I was applying the character random numbers I mixed up some values. This would be a lot of work to fix. I think I know how to fix it since the data is on Excel file. I could just apply some rules to the cells. The problem is that this would be a lot of work. I can't promise I can fix this anytime soon. I'll check it though...