I think that chest shows up randomly in Cellars too. I just checked festering lair and no luck, but the Dank Cellar (Where you save Darlet) had a chest.
https://a.pomf.cat/slcfjv.jpg
https://a.pomf.cat/norham.jpg
I couldnt find the Craigs Crags chest unless they moved it to be part of east march. Checked Hallowed Hill, didn’t show up there.