Not sure what you mean, but I could probably oneshot medium or maybe even hard without using any of my prophetic prescience. I'd bet most of the people who regularly play on insane could oneshot most campaigns on medium or below. And it's not like our 'skillset' is above what a real combat pilot should have. It's probably below that.
Then again, even furyAI isn't good enough to give the player a real challenge even on insane. You still have to use superior numbers and conlifcting objectives.
Though if this was 'real life' the only difficulty option would be insane, as that's the only difficulty that doesn't give the player artificial damage reduction and magic reactors that refill your shields and guns 2 times faster.
Okay, this is feedback from a guy who's been playing Freespace 2 for quite some time, but really just pops in now and then to enjoy the new content.
It's very, very clear these mods are designed for Freespace 2, and I do mean Freespace 2, veterans.
Now that's fine, as long as you understand that for 90% of players, they are going to fail, multiple times, completing these missions. I did, and I've done Ironman runs of FS1 and FS2 on medium (death = campaign restart).
In AoA, you could complete the game without much difficulty, it was expertly crafted, and in general gave you time to react to new situations. But if you don't know that Ravana is jumping behind the Temerarie? You're going to lose, period.
WiH is generally much harder than that. You WILL fail each mission over and over. The mission to engage the Hood had so many directives, it's really not possible to defeat unless you know exactly what to do and when. Nyx fighters are tough as nails and can chew you up in seconds. Staying within a Frigate's flak cover shouldn't mean, "hiding behind a hull until half of them are dead." Failing to disarm a beam or an AWACS is a death sentence.
Now, trial and error is an acceptable way to make a game difficult. Look at Dark Souls. That requires "Edge of Tomorrow" like reflexes, planning, etc.
But it is important to state that for an average person that plays FS2, and makes the jump to WiH, the difficulty is going to be jacked. I realize this is a conscious choice. But, well, "ALPHA ONE DO EVERYTHING" is a perfectly legitimate critique of Act 3, even for it's great highs. And I played Act 3 before the training missions were added!

The easiest way to deal with this would be to have one or two "sub battles" within a mission. There should also be enough time to complete them, such as breaking off to deal with a large flanking bomber force with escort. Or a small cruiser group coming in from above. Crucial to the battle, but not in the middle of a meat grinder all the time.
For specifics, the Hood mission's difficulty for me was borked. Same with the platform defense mission where you had to disarm the beams of the GTVA corvette.
The end of Act 2 was great with the battle with the Carthage. Her Finest Hour and the Elder Assassination mission were fine in their polished form. Harsh, but fair.