You would have to check your state's expungement law. Some states will not expunge certain crimes, and Kidnapping may be among them.
In addition - the question arises as to whether or not you were charged with the FEDERAL offense or a state statute. It may make all the difference in the world when you (or your attorney) wish to take action on it.
Since there is no court order and you were never married it is the mother that have custody. He can be charged with kidnapping.
kidnapping was never allowed
The money (or property) that was put up and accepted by the court as his bail bond is forfeited to the court, and the absconder will have the charge of fugitive added to his other charge(s).
If the case is closed by the court it can never be opened again.
If listed on a current or archived docket then yes. Some cases never see the inside of a court room. For instance there may be a case number but no date or a case may be threatened then settled out of court. Cases listed on a docket will be reviewed by a judge in open court and the clerk/recorder will log all of these into the public record.
If you go to the court records that ordered the sealing and try to determine who asked for the sealing it may give you a clue, but because the record IS sealed you may never know for sure.
It will never be sealed unless you apply for expungement.
You should never go into court without an attorney. Particularly when there are criminal charges involved.
Probation is a good possibility.
The walls of a house are never completely "sealed". There are always slots where insects get in and out.
If this is a criminal charge - I have never heard of it. If this is a civil case, you can bring it to court at any time.
You can't inherit from sealed classes.