I think there might be something going on with the FSPort version of this mission at the moment. I'm playing on medium and got through FSPort without too much difficulty, but despite racking up 11 or 15 kills on this mission, I've yet to have delta take out a SINGLE reactor. After about 8 or 9 minutes delta dies, with all 5 reactors still intact and the Lucifer at ~98%. Given how all the walkthroughs talk about how this mission is insanely easy, I feel like something weird is going on. I've never even seen delta hit the Lucifer. Can a vet give this a try and see if I'm crazy?
Edit: Just tried again. Started with all 16 allies at 100% health. Had 11 kills with 3 minutes left when the last delta went down. 1 reactor down, Luci at 66%. We were pretty much taking down the fighters faster than they were spawning, most of the time there was maybe 1 or 2 manticores up. Delta just seems useless. It's really frustrating!
Edit again: I just watched the 2nd youtube video you posted QuantamDelta. You did a nice job, but I'm killing the fighters at at least that rate and it just seems that Delta is doing NOTHING on medium. Something weird is going on...
ISSUE IDENTIFIED (I think): I put the game on very easy, sped up time, and just followed the deltas to see what they were doing. They almost never fire their bombs. They park themselves ~1000m from the Lucifer and fire their guns over and over. Every 3 minutes or so, one will fire a bomb off. There seems to be an issue with their AI. In the game where I watched them (very easy), they took out 2 reactors in the 10 minutes, the second with 1 minute left. The other 3 reactors were at ~60%, 90%, and 90%.