Lets keep opinions over things like ballistics and formations out of this and focus on what just doesn’t work.
Corvette Behaviour: currently multi-gun corvettes and heavy corvettes especially need their combat behaviour changed, they don’t work (they’re not gunships)…heavy corvettes can’t aim or hit anything and multi-guns only use half their guns and don’t fire at multiple targets.
Anti-corvette weaponry for HW1 races is pretty poor, with non-functioning heavy corvettes and assault frigates that seem better at taking out fighters but miss corvettes (They must have copied the vaygr assault frigate guns and forgot to tweak them, in hw1 assaults were bad at killing fighters), this is a blind spot that leaves them vulnerable especially to the HW2 races.
Much of the little annoying errors that were in HW2 have remained in HW remasted, Vaygr minelayers and lasers corvettes have swapped build icons and heavy missile batteries on battlecruisers are described as “anti-fighter” when they don’t even shoot at fighters.
Balance, the other than the above minor balances changes and upgrades in particular need to be accounted for when playing HW1vHW2.