So, yesterday I decided to enter tier 4 of the JJ event at 1x speed because of Maul's apparent insta-kill tendency, it worked. My guild today started the raid, when I was on my 3rd battle, I figured I could try it out there. It seems to be a big help. Most of the time, the battle finishes after the 1st or 2nd wave. I tried out Lumi Jedi at 1x speed, it went smoothly, the only problem I had was the difficulty (2/5 of the team are at G12, no Lumi zeta yet). I did my 4th battle at 1x speed - B2, DDK, Magma - no technical issues. 5th battle was with full Gungans, again, I only lost because of the difficulty. I don't know if this is an actual fix or just a fluke, so I don't know whether it will help.
P.S. There also seems to be a bug where part of Phalanx's unique doesn't work. It's supposed to make the Gungans immune to Protection Disruption while the Generator is active, but the enemy still manages to land it.