(How far "else"? We're not accidentally robbing a bank or something?)

No. The temple was discovered in a remote location. It is a rediscovered ancient temple.

This area you are exploring is separate from that and even older.

"Let's get through the wall than and see what is here." Pepin says and if noone stops him he'll start working the wall with his warhammer.

"Seems, fitting, being lead to a hoard fit for a dragon, after fighting dragons that control goblins, from a black tent, and dracoliches, but what are we up against? That is the question. I heard my kin sit to absorb the essence of metal and magic."   he says as he watches the hammer blow.

((Pepin would use what he thinks works best to get through the wall quickly; so either warhammer (maybe with booming blade) or masons tools.

Is a roll needed?))

Quote from Secretfool >>

((Pepin would use what he thinks works best to get through the wall quickly; so either warhammer (maybe with booming blade) or masons tools.

Is a roll needed?))

( Z has a Crowbar and Hammer in his pack which he is happy to offer, if it's of any help)

Since you are not in the middle of combat or anything I'm not going to have you make a lot of rolls to break through the wall, it will take some time and quite a few swings but you are able to eventually break through the 6-inch thick stone wall.

After the hard work Pepin takes a moment to catch his brearth before moving through the hole into the treasure chamber.

Each footstep makes a little noise and slides slightly as the coins chink and shift under your feet. It is considered difficult terrain.

With a treasure hoard this big, Pepin wonders if maybe other parts of the Orrory of the Wanderer could be here. He starts to look around for any of them.

Investigation: 13+4 (Guidance)+flash of genius= 22

Yes indeed, after a few moments of searching you find another part of the Orrory of the Wanderer.

Randall:

Likewise beginning to search, Randall looks for items of use and/or power, portable monetary treasure (gems, etc), and clues as to the origin of this treasure.

Perception:  23

Post which gems (type, value etc.) you are searching for and you think some of this treasure may of belonged to the Black Dragon/Dracolich you defeated. All treasure hordes grow over time but this one looks like a treasure horde was added to a treasure horde, and then another, and another etc.

Randall:

As many powerful healing spells require gems of great purity  and value, Randall searches for diamonds.  For items of power, he would be interested in anything dedicated to these holy gods—specifically Lathander—and magical plate and shield would be nice.

Pepin is extremely happy with finding the dimensional loop; he only needs to find two more components and the Orrory itself now to complete it.

Zenodor follows the others into the treasury and looks for any interesting magical items.

He then cast Demiplane to create a small treasury room the group can access from here, and later from the city. A door magically appears on a nearby wall.

While he does so, he says to the others : "Let us gather up what we can. Any wealth and items which we cannot easily carried can be stored in there. We can then later access this demiplane from the city. I can keep this open for an hour at most."

Once his search for magical items is over, he will just carry / throw / shovel gold and gems into the Demiplane treasury 

Randall finds several nice diamonds and gemstones, while looking a yellow gemstone catches his eye, it is half buried under some coins but when you brush them aside you see the gem is embedded in the chest of a polished suit of armor.

Pepin notices a finely crafted book near where he found a part of the Orrory.

Zenodor is excited to start shoveling as much of the treasure as he can into the demiplane but that wavers a little as he glances around the 80 foot by 80 foot room packed with mounds of coins and other valuable objects and at the 30 foot by 30 foot demiplane.

Randall:

Digging up the armor, Randall examines it closely, hoping to perhaps find a matching shield.  Regardless, he spends some time with the armor, looking especially at any religious iconography.

He puts the diamonds with his other spell components, confident his powerful spells will have the components needed.

Pepin quickly picks up the book to see what it is about, and why it is so beautifully crafted.

After which he'll help Zenodor to move treasure to the demiplane.