Reflected signals return to earth after 50 or more years, but the signals are about a billion times too weak for us to receve them. A billion times improvement in the technology, seems very improbable, ever, as the miscellanious noise is much stronger than the bounced signal.
Somewhat different is however workable with today's technology. We transmit our math, science and language lessons to ET who lives several light years away. ET receives and records the information; then transmits it in approximately the opposite dirrection to another ET who also records and sends in about the opposite direction. Occasionally an ET transmits an old recording in some direction because ET's scientists have determined some of the information is valuable to somebody, so the Information could return to Earth 50 years or even 50,000 years after it was sent with only minor errors. I call this communications system the Galactic Net. As far as I know, I am the inventor, but possibly the galactic net has been operating for millions of years, preserving the wisdom of long dead civilizations. Neil