Where Would I Find Out Who Has The Most Galleon's Graveyard Completions?

Yeah, because I have been recently grinding it a lot with many other players, helping out and stuff, so I just want to figure out- see if I can go for the record or something

 

Im sure there isnt a dungeon leaderboard but players have stats of completed dungeons on their stats page

 

There are no 'Leader Boards' For completed dungeons, or even a convenient way find who has completed the most dungeons, but you can just look at the Guiness World Records Thread here:
https://forums.wynncraft.com/threads/wynncraft-world-records-edition-4-records-updated.195854/
If you would look at the Game Records Section, you will see some of the most active players

Look them up at the players section:
https://wynncraft.com/stats
So then you can atleast see what a 'high' amount of dungeon runs is.
Or just go into the player section Of Wynncraft stats and see the highest level players.
See there dungeon runs here:

Another thing you can do is just ask on the Wynncraft World Records thread for that section to be added, and lots of people will comment saying 'I think I have the most"
https://forums.wynncraft.com/threads/wynncraft-world-records-edition-4-records-updated.195854/

 

Considering you've only done it 5 times, I'm just gonna guess you're not even close to the world record.