I was thinking that I should create a helper function like path for Scavenger of the Sands as the line is getting longer and longer, would like to add a different atlas as well. Do you think it's a good idea?
Also should these records be moved out of the junk? Out of the treasure file even?

True, alright.
By the way I also included one of Jani's Get Hek'd chest, do you think it should be kept?
On one hand it's a chest, on the other the rest of the achievement is different, like actual quests and such, so probably no place for them in this addon.
What is your policy for these smaller achievements?

It's specific to just that little segment, so I'd be inclined to not bother with an extra helper. It's when something's going to spring up scattered through the files that a helper makes more sense to me.

That said! It is indeed not junk, because "junk" in this addon's parlance means "something which doesn't contribute to an achievement", rather than the game's meaning of "a gray item".

That makes sense.
But then is there a need to have an option to disable only it?

I wouldn't bother. It's not like many of the other achievement-treasures are anything but a few grays, after all.

I would love the option to not show the 'Scavenger of the Sands' treasures or others associated with specific achievements. Could you put a checkbox in the 'What to display' section for each achievement for which you've added treasures?