Are human players able to kill player 7 units or is it a computer player killing another computer player?

If its human then yes you would still need to subtract the killscore as jack stated because even tho player 8 has to suffer a death for your custom score to activate, whichever human player killed a player 7 unit will automatically be given a killscore for killing that p7 unit. This killscore will add onto the killscore amount of the next unit that player kills. For example...

P1 kills p7 ling = 50 killscore
p1 kills p8 queen = 800 killscore

p1 killscore at time of custom score trigger = 850 killscore

Obvioustly seeing it laid out now you should understand that there are no units that have an 850 killscore which will totally mess up your custom score triggers because now this player stands a chance of never getting his killscore swapped to experience.

However, if its a computer killing a computer. I would imagine that you have computers disabled from leaderboards for your spec forces and that there is no use of an exp system for computer players. In this case, no you do not need to worry about subtracting or rewarding the computers for your system. But if your system is based off the computer suffering deaths and the deaths are reset then you would have to reset the deaths received from a computer killing another computer.

Make sense or did i confuse you some more?

This isn't entirely correct as the system should be using "At Least", so the player will still get the queen kill. It just makes the chance of incorrect experience being given out higher, as the chance of players having the same killscore as a unit that someone else killed is higher.

True, if he's using at least he will get rewarded. I'm used to using exact for exp systems so it slipped my mind. But yeah in this case as Jack just corrected me on if you're using at least it will give you an incorrect experience amount. If you're using exact then it will be as i described originally above.

No, using At Least will mean it gives correct experience. However, the slim chance of two players' killscores and player 8's dead units coinciding to give incorrect results is increased.

ahhh true again.

Seeing as this is a spec forces map, can i ask why not just use points leaderboard (kills and razings). This will show the default killscore for each unit that has been killed as listed on the links earlier provided and will keep adding them on top of each other without the use of triggers for p8 deaths. A lot less time consuming as the only triggering you should have to write is swapping those killscore points for minerals.

Are you looking to replicate other spec forces exp systems or are you looking to completely rehaul it with your own variation?