Hafelfinger is a 1984 decision and there have been a number of decisions since based upon it. None of them are indicative of how you are interpreting it from what I've read so far.
Upon charging in court, there is a record of the original charges that are available in CCIC/NCIC that the Instacheck techs in CBI immediately see, to include whether they are felonies or misdemeanors. They then have to research the finality of the case to its conclusion through the same court record. If that record shows a dismissal, they will authorize a purchase. Court records are only sealed from the general public, not law enforcement, so your point about sealing isn't correct.