Ignore the impulse comment, I'm retarded. Severely considering the number of physics classes I've slept through.
ApplyImpulseFromSpawner is another force application like magnetize. It's applying force over time(the definition of impulse when one isn't having an apocalyptic brain fart) so the mass of the object is going to alter how fast it moves. Each ship has it's own mass value.
See Telekinetic Push for the vanilla implementation of the function, the one that blows away fighters.
The predictably consistent one is InitializeMovementTowardLastSpawner, BuffRepulsionFieldTarget is an example of this one. All ships will move at the same rate, something you're in dire need of in order to time their explosion.
The problem with things being delayed using the OnDelay trigger is that you're not accounting for the game design. Each tier triggers independently. Your buff reference inside another buff is triggered at a different time, it has a delayed effect. To have things coincide, they have to be on the same level. For two separate files to enact simultaneously, you would trigger them from the same parent. Getting them to enact at the same time as their parent is simply impossible.
Because if this, you're always going to have a delay on child actions. So, you have to time it. You have to apply and set off the explosions at the correct ranges to get them to line up, and it's going to be hellishly fun. As soon as you run it on a slower(or faster if yours is inadequate for maximum performance) computer, it's going to be wrong again. There's no good substitution for magnetize with it's impact code.
If you want an example of buffs with tolerances, download the SOA2 mod and peek at my work. The Jem'Hadar specific buffs on Dominion capital ships, a lot of the Borg abilities, I have lots of interconnected systems that alter or prevent usage entirely. The tolerance is how wide the delay time has to be on things for them to actually interrupt in the appropriate conditions. Too short, and your ships magically receive gifts they weren't supposed to get, mysteriously blow up, switch sides, all kinds of wonderful stuff that isn't intended.
If I weren't on a stone age computer my curiosity to see it work would have it done already, but alas I can't get something like this to function locally. It was hell just getting fighters to self magnetize for the Borg.