Other NPCs have been able to see the Moogle NPCs and they likely didn't all have the Echo, so I don't think you have to worry about that.
Also, since others mentioned something about the Echo feeling "tacked-on" to characters, I think part of that may be just that not everyone understands how it's supposed to work. It was only very recently that Sounssy corrected me on what I thought were the minimal parts of it, so my character hasn't had any "visions" in her background (though with where she is now, it would be an interesting time to start). And things like fighting primals are often "off-screen."
Also, since others mentioned something about the Echo feeling "tacked-on" to characters, I think part of that may be just that not everyone understands how it's supposed to work. It was only very recently that Sounssy corrected me on what I thought were the minimal parts of it, so my character hasn't had any "visions" in her background (though with where she is now, it would be an interesting time to start). And things like fighting primals are often "off-screen."