Yeah, it's mentioned repeatedly throughout the game's entire storyline from even 1.0 that the Echo is transcending the boundaries of the soul, both the user's own and the souls of others. This manifests in various ways, but specifically viewing another person's memories as if they themselves had lived them, understanding another language without actually having learned it, being immune to tempering by a Primal, and much more.

As this information is spread out throughout the game's story it would take me forever to track down the screenshots I took which I could quote from specifically, but I can steer you in the right direction - the very first meeting you have with Minfilia when you first joined the Scions she explained this specifically. So yeah, as Kaiser stated, it's made very clear the Echo is soul powered, and because the soul (as in, life itself) comes from Hydaelyn, the Echo can only be gifted to someone born from Hydaelyn - an artificial construct like an automaton simply would not have access to that, no matter how much you try to handwave it away.