I have a feeling that your filling might be correct. Vid tried to use the num-kills sexp and it didn't work too well. Well the mission works the way it is so it's not a real problem. It just has 2 event's that only half work that don't effect the outcome at all. It can always be released the way it is and fixed somewhere done the road.
I just looked at the asteroid field in V's Lite Asteroid dogfight. It doesn't have the same behavior as TBP's asteroid field even when run in FS2_Open 3.6.9. Could the behavior have something to do with the size of the asteroids? This is for an active field. Didn't' try a passive one in FS2.
Going to finish checking a couple of missions, split the Drakh ones into a gunship and regular versions and work on the gauntlet and asteroid fields. If I get those behaving then that will only leave something like 6 missions that don't do what they are supposed to. 2 Vorlon base ones, the Whitestar one, and the Shadow heavy dogfight spawn points.