So the collection book currently shows how many units an achievement gives you, but not how much EXP it gives out. So I think there should be a HUD showing the amount of EXP you would receive when you get the achievement.
I think all achievements just give 1k xp, I haven’t actually payed attention that much, but I think it’s a common payout.
I don’t know how much they give but I know they don’t all give 1k
Some BR achievements give like 5K, some achievements give about 1K or just 500.