Achievement bug

Time: 9:48PM on 26/3/2016
Frequency: N/A
My world name: Odin
His world name: Zodiark
My character name: Fire Hands
His character name: Astral Dee
Monster name: Ravana
Class/Level: Scholar/60
Party or solo: Party
In-game time: 9:48PM on 26/3/2016
Area and coordinates: Ravana

What happened?
Simple, we went into trial roulette and at the very end 'Astral Dee' somehow unlocked three achievements that in no way could be obtained in just completing the trial roulette instance.

'Astral Dee' unlocked 'To The Dungeons IV', 'To The Dungeons V' and To The Dungeons VI' sequentially at the end of our Ravana trial instance.

How is this even possible?

I attached an image as proof.

http://i.imgur.com/FS83w1Z.jpg


Link to original image (bigger/clearer): http://i.imgur.com/FS83w1Z.jpg

If they hadn't ran a dungeon since the 3 tiers were added, but had completed enough to fulfill the requirements, it's possible. Similar to the kill x mobs achievements - you may have killed 500,000 before a 'kill 500,000' is added. So when you log on, and kill a mob (now your 500,001 mob) you will activate the achievement.

They had met the requirements before Heavensward launched, so those achievements didn't exist yet. Any achievements you meet the requirements for before they were added won't be given to you until you do one more of whatever the requirement is. Thok ast Thok is the first instance you enter in Heavensward, so it makes perfect sense that they would get those achievements there.