In Encounter 2b of Hallowing Fire (Mists of Bilehall), the bottom side of the map indicates that tile 8B should be used as the Sanctum, however the reference made below states 82B. Which one is correct?

Tile 82B looks like it could also be the Sanctum.

Can I assume the map design takes precedence over the text reference?

Checking...

It's definitely a typo, 8B is the sanctum, because 82B isn't even part of that map.

I have no idea whether FFG uses a vault-like tool in their official map construction. If they do, it is MUCH simpler to make a typo of a number (82 vs 8) than to choose a wrong map piece, including an endcap.