Okay so I was doing research about the realms because now you put it in my mind (WHEN I SHOULD'VE BEEN WRITNG)
And pretty much in Possession it said 16 realms, not 17. But some people debate it meant 16 OUTSIDE Ninjago. But when I go to Ninjago Wiki it shows 14 realms and then 3 realms that are unknown. So 17.
But...honestly... If 3 are still unknown I probably won't change it to 17 until those 3 realms are named because yeah.
But TECHNICALLY you were right, LOL.