Hello @xeriphin, Let me discuss your problems.
1. The bug that allowed the emperor to shoot through walls is solved, he cannot shoot through walls anymore. He didn't get a nerf since launch, he only got a buff after the bug was fixed. The emperor is one of the fastest moving characters when timing his jump and dodge roll correctly. He is therefore hard to hit and can fly high up in the air with his force lightning. He is definitely NOT weak, he can recover massive amounts of health in a short amount of time. In GA, the emperor can be alive for the whole match, getting killstreak up to approx. 70 kills per match. IMO, his movements should be tweaked so he can't escape so quickly.
2. Freezing opponents in HvV is just using the abilities. There are freeze/shock abilities on both the light and dark side. These attacks can be blocked (by lightsaber) or dodged by combat roll. I suggest changing your playstyle a bit to adjust to which enemy you are encountering. So if you want to defeat chewie, you don't walk up to him in the upon from the front, but try to outmanouvre him.
3.Reys Mind trick is a unique and creative ability that can be very annoying to enemies, but however, does on its own no damage whatsoever. If you are trapped in the mind trick (which you can block and dodge) you should try to move away from Rey for that period of time. Try to dodge, or jump (with palps) to get out of the reach. It requires some practice and doesn't require any tweaks IMO.