Joanne,

>> What if the Helper or the one who is in the Afterlife is a foreigner when I am doing retrieval? Is language a barrier for our communication? <<

Your question assumes that hearing within a nonphysical reality is the same as hearing within a physical reality.  In nonphysical reality you do not have any physical ears, so hearing is probably not quite what you expect.

From my experience I would say a component of our consciousness ( Perceiver) receives feelings, emotions, thoughts, impressions, etc. and a separate component of our consciousness ( Interpreter) converts these into what we experience the sound within nonphysical realities.

The language of feelings, emotions, thoughts, impressions, etc. is universal.  The Interpreter converts these into the language of the listener.  So in my opinion languages or not a barrier to communication within nonphysical realities. 

>> Has anyone ever encountered such situation? <<

Many, many times with no barrier to communication

Bruce