Quite possible. Where can I locate roughly the HPFR regulator ?....................taAre you sure it's coming from the EGR valve area? It's normal for the HPFR pressure regulator to buzz. It's not always audible, but some are more noisy than others.
This used to be known as the Donald duck noise. It was discussed in length years ago with videos posted. Don't know if they'll still be on.
Mine does it quite regularly, and I've heard others do it. Nothing to worry about.
Mike