If so, this may create an accounting nightmare for Lusche because the number of deaths will no long match the number of kills. Oh horrors.

No, no horror at all. Due to several reasons, there is always a small mismatch between kills & deaths, but in the overall scheme of things it doesn't matter

The kills are lost for player score, but not for plane stats. Plane stats are updated in real time, if you kill something the kill is being written to the database immediately. You can check this during a sortie, see how the web Pilot Stats change after you made a kill.
The score however is only update when the sortie is over, either by "exit flight" or a death or a non-server disco. If the server resets, this sortie never has happened at all - but AFAIK the plane stats are not being altered.