Is there a way to add a custom tile entity to positions that have vanilla blocks? I have tried to do so in my custom tile entity, however when I go back and get the added tile entity with:

world.getTileEntity(pos)

it returns null.

Just after I add it to the world, I can get it using that method, but it is like they disappear; the methods still run and there are still tile entities with those positions, but there is no way to get to them via position. I debugged by adding them to a hashmap with their positions and could get the tile entity but still returned null upon trying their corresponding positions.

 

Here is a picture:

 

Sadly you cannot place a TileEntity on a vanilla block that doesn't already have a TileEntity. But you can store a Map of BlockPos as the Key and a List of BlockPos as the value and cross reference the lists contained in the Map in the PlayerInteractEvent.RightClickBlock. And if it is in a List perform the action you want for the TileEntity at the key BlockPos.