Couldn't they just shoot down the balloons holding up the net with the ship's cannons? Also assuming they couldn't, why not shoot the generator? They knew where it was and Raz was able to take it off line by bludgeoning it with his gun. Cannon fire would have got job done.
First issue: Centurion's main guns aren't able to target the balloons! The ship's main guns and their sighting systems were intended to target enemy ships and/or fortifications, not floating balloons on exposed electrical cables. Even though the guns are powerful enough to send shells into the sky, the problem comes down to the issue of practical elevation of the guns. If you somehow get the barrels to elevate to a 60 degree or greater angle from the horizontal plane, the guns' breech-blocks may wind up RIPPING THROUGH THE DECK PLATES during the recoil phase, which would cause nasty damage to the ship itself! There is a VERY good reason why you can't shoot airships with regular surface vessels. And forget sending a sniper to shoot the balloons, you'd cause Forseti to order an all-out assault (as he threatened) once the first balloon was felled.
Second issue: Forget targeting the generator with the main guns. Forseti anticipated that someone would try that when he set the trap, so he hid the generator where the ship can't see it, he made it practically suicide for anyone to get close enough to spot for the ship by placing lots of troops around the generator, and geographically he placed it where the artillery shells probably won't land (namely that the generator is surrounded by natural obstacles that would get in the way of the projectiles)! Give the man some credit!
So, here's a question. We need to have a story, of course, that's a given for a game - but doesn't the game itself seem as though it makes Squad E's very presence in Northern Cross detrimental to the Cygnus Fleet? If they weren't there, then by all indications the plan would have likely gone off without a hitch. The only link to the fleet the Empire had was Leena, and the only two people in the Empire who knew (sort of) about the ships prior to the Centurion rescuing Squads E and F from certain death were Forseti and Belgar. If Squad E never got involved, or if at least Leena didn't, the Empire would have next to no way of even finding out that three snow cruisers were barrelling towards their capital until it was much too late, and the only semi-reliable testimony they'd ever have with regards to their existence would be the whispers of isolated islanders.
Let's don't assume Forseti's got only plan A and only one spy. He's got LOTS of spies all over the place, as one of the "innocent villagers" picked up by Centurion was an X-0 operative who handed Leena the transceiver. Remember, radio signal interception is a definite thing, and Forseti would have gotten another person near Centurion as soon as he could if Squad E hadn't gotten aboard (do recall that Walz's report about nearly getting ship cannons in the face might have been copied for X-0, as X-0 specializes in making secret weapons and capturing or destroying enemy secret weapons for that matter). Leena being aboard Centurion was a stroke of luck for Forseti, so he chose to plan accordingly ("Since Squad E was rescued by the snow cruisers, I can assume that Leena is aboard ONE of them"). One can assume that there were spies on Comet and Cavalier as well, perhaps blackmailed into giving their positions to Forseti.
There's also the fact that Forseti was able to get his agent onto the Centurion to give Kai the transmitter in the first place. It seems he didn't have much trouble figuring out where the Cygnus fleet was.
Then again, he was probably intercepting their communications already, so one could explain he needed to get an agent to Kai in order to have a precise location of the Cygnus ships at any time of day (otherwise he'd wind up sending his troops around in circles trying to find the snow cruisers).
No airplanes exist on the battlefield, so, why do both sides have paratroopers?
From where do the paratroops jump, a high wall?
Alright, alright, keep your pants on, there's a perfectly good explanation for this. Parachutes were probably developed alongside balloons in this universe. Observation balloons tasked with artillery spotting were at risk of getting shot down (they probably don't float high enough to evade gunfire). If the balloon went down quickly, the soldiers in the balloon's basket would likely die if they didn't bail out. Parachutists are harder to hit than stationary balloons. As for paratroopers, it is likely that someone decided to develop airships and perhaps a unit of parachuting infantry. The big drawback of the era is that rigid-frame airships are too freakishly expensive to send to the frontlines, thus restricting their deployment to special operations (and in the case of the Empire, only X-0 has paratroops at all). Claude, in contrast, merely repurposed the Centurion's artillery-spotting hot-air balloon for use as a paratrooper transport. The parachutes were meant for artillery spotters (and presumably there are at least a dozen or so sailors trained on parachutes aboard the ship), which explains why enough parachutes were available for Claude and whomever else dropped in on the fortress.
Lighter than air flight exists already. There's even a giant airship attacking Gallia in VC2. In fact, the glossary entry notes that they're dropped from either balloons or airships.
Discrepancy about who's "The Strongest"
According to Selveria and the in-game glossary, Crymaria is said to be the strongest among the Valkyur. Except there's a major discrepancy in that assertion: it completely disregards Alicia.
During the "Two Valkyur" DLC, Selvaria and Crymaria fought each other to a standstill. Yet, when she tried to fight Alicia (VC1), Alicia nearly ended the "fight" with her opening shot. Their second encounter was even worse, since Alicia's first shot not only shattered Selvaria's shield, it sent Selvaria rag dolling across the battlefield and left her barely able to stand - and Alicia was more unfocused than Crymaria was, due to only recently discovering her powers. Wouldn't that mean Alicia was the strongest?
Look at what Crymaria does when it comes to your final battle with her; she covers the entire battlefield with a hellish blizzard, and the area closest to her has a damage-over-time and slowdown effect. Alicia never demonstrates any ability on that scale. Or compare what damage they were able to do against large targets: Alicia's strongest attack makes a large but non-debilitating hole in the Marmota, while Crymaria destroys the Comet completely. Alicia has better control over her powers, and might be able to focus an attack against a single small target better, but she can't put out anywhere near the kind of energy Crymaria can.
Revision: After (recently) finishing VC1, we can safely assume that Alicia could have easily destroyed the Marmota. Otherwise, Maximillion wouldn't have panicked and ordered his helmsman to change course, when saw she was preparing to use the Final Flame. It took Welkin to talk her out of going through with it.
Alicia could potentially have destroyed the Marmota with her Final Flame, which is shown to be the greatest possible power output a Valkyria can make. Crymaria destroyed the Comet without having to use her Final Flame, meaning Alicia would have had to push herself to her highest limit to match the destructiveness Crymaria could achieve with her normal attacks. Alicia is still only Weak, but Skilled compared to Crymaria.
She didn't need to use the Final Flame, she choose to because she had only recently been awakened as a Valkyur. A fact which she openly admitted to Sylveria, because Sylveria was more experienced in how to use her powers. Alicia even hoped that Sylveria would mentor her, but she refused. With proper tutelage, it's very likely that Alicia could have done the same as Crymaria. Otherwise, how do you explain Crymaria being able to sink the Comet, but unable to defeat Sylveria? Whereas Alicia 1-shot Sylveria - literally without trying - in a matter of seconds and her presence made Maximillion beat a hasty retreat.
Given that the moniker was given even before Alicia's power was even revealed, I think they just didn't know about Alicia.
But the in-game personnel files are omniscient (in regard to the series' lore) and Crymaria's file says she's the strongest Valkyur of all, despite being unable to defeat Sylveria. Alicia did twice and made it look easy both times. In seconds.