I decided to try to get all the achievements for sins as I had some time ahead of me, but it seems some of them are broken and cannot be accessed by following their description.
For instance :
"Destroy 20 planets in one single game", I thought it was related to the vasari sttc power (I had already bombed countless planets on previous games with huge maps before so to me it was something different). If yes, then it probably does not work as I received the achievement at a moment I was simply conquering a planet and I had stripped only 2 or 3 before.
On the other hand, I am trying to get the one with the Advent where you need to search all techs from the harmony tree and none from hostility. As I had doubts, I decided to only research harmony and none of all other tres except fleet supply. When I unlocked the last tech, the award was not granted. I also made sure that the IA was still alive when I did it even if I am not sure it matters (I know one achievement has not been granted to me before as I wiped out all IAs then did the job peacefully so I thought it was necessary no one already won the game when meeting the conditions).
In some older posts, it is said that this achievement and some others (like the 1000 pirates one) are broken as 0% of players had it. But some players do have it now so am I doing it wrong ?
Thanks for your answers