It's not a bug you have only misunderstood how to do it.
There are two kinds of buildings visible on the map, the teleports and the Incantation Shrines.
To be able speak to the dead you have to find one of these Incantation Shrines, then you step upon it press ENTER and write vox mortem then ENTER again.
This will give you an temporary aura, that as long as it lasts will let you understand and speak the language of the dead.
.
yup, but i already finish the ghost quest ( talk with all ghost of the game ) and the reward is a piece of S***. stats of full set are posted on the set thread