In my opinion:
Proxy : Bump speed back up to pre-patch. Keep shotgun as is.
Possibly lower mine range/damage.
Aura: Lower health station health. Or maybe give her health decay so that she really needs to stay in the magic circle. Bring in more counters to Aura, such as Nader, or EMP grenade characters.
You could possibly have the health station jam the guns of people in the circle when it is destroyed, forcing a reload…however, this would also work on the other team as well. While this would typically hurt the team deploying the health station, it could also be used creatively as an asset as well. For example a Proxy could place a mine, and an Aura could place a health station beside it. When an enemy player trips the mine, they also get stunned by the health station at the same time. Combining two enemy abilities for a bigger effect.
Fragger: Maybe lower fire rate, grenade radius. Lower objective completion speed so that he is practically useless in that regard.
Skyhammer: Keep as is.
Sawbonez: Increase speed a bit. Give him a shorter paddle charge time, so that he can pick up people faster, with more health than Aura does.
Maybe give him a unique SMG that doesn’t require reloading at all. Maybe give him a faster objective completion rate.
Arty: Give him a quicker ammo pack cool down.
Make all burst file rifles better from the hip. (More accuracy and power, but slower fire rate to compensate.)