The PlayerObjectPlace and PlayerObjectRemove events already provide the worldposition (accessible with event.position.x, event.position.y, event.position.z).
The AreaUtils:isPointInArea3D() accepts different parameters, so for objects you can use
[lua]AreaUtils:isPointInArea3D(event.position, areax, areay, areaz, areasizex, areasizey, areasizez)
--or alternatively, probably you need this function:
AreaUtils:isPointInArea3D(event.position, startChunkpositionX, startChunkpositionY, startChunkpositionZ, startBlockpositionX, startBlockpositionY, startBlockpositionZ, endChunkpositionX, endChunkpositionY, endChunkpositionZ, endBlockpositionX, endBlockpositionY, endBlockpositionZ)
[/lua]
A wiki is really needed
Btw., you can add me in Steam, you can always ask a question about a function or event there, in most cases I can answer much faster then^^