HW1 fighters and corvettes are weak as pants right now. HW2’s strike craft outclass them in every single way because they fight in squadrons and are also faster. HW1 factions just don’t have any viable anti-fighter strategies that don’t revolve around spamming defenders and multiguns, and even then this feels like more of a stop-gap measure than an actual strategic fleet composition choice.
You could eliminate almost all of the balance issues that exist (or at least put us well on the right track to doing so) by putting the fighters and corvettes of HW1 races into squadrons and making them have the flight behaviours of HW2’s strike craft. Having them on their own just doesn’t make any sense now that the fuel system is gone.
The support ships are also completely useless with fighters being weak and the fuel system being gone. My idea on how to balance them after putting the fighters into squadrons would be to give both of them greater carrying capacity and also (optionally) the same benefits of the Vaygr command corvette. You can use them as cheap hyperspacing carriers for your strike craft that way, and they’d also benefit other ships too.
If you wanted to lean towards more asymmetrical balance in the style of HW2, you could give one of them an AOE repair of some kind and the other the command corvette buffs.
This isn’t related directly to fighters, but it seems like a lot of the balance discussion seems to be veterans of HW1 and veterans of HW2 yelling at eachother about which game has better mechanics. I think with the HW1 races being basically ported into HW2’s engine and thus being forced to fight on HW2’s terms, too much is already different to balance the game around HW1’s gameplay style. You really have no choice but to balance the Taiidan and Kushan around the HW2 factions.