I tried to avoid getting into the question of mass vs. flavor eigenstates. Neutrinos are leptons, anti-neutrinos are anti-leptons. Yes, we can go into mroe detail and talk about individual flavors, but I deliberately avoided doing this.You talked about actual leptons coming out of actual processes that are detected in the lab. Don't those processes normally involve a specific flavor of lepton? If so, it would seem like they should also involve a specific flavor of neutrino.