Hi Amzub,
We printed out the email confirmation from the nz police when they processed my husband's police certificate. I put a little sticky note by the part that mentioned that they sent it to the us embassy etc etc. We also attached a copy of Police Vetting form that we filled out that. Ours went through with no issues. They received it on June 12th.
note* We are also paper based application as we started this in 2017. We have kept our application on hold at NVC until now.