You should smoke the event. I did it with magma, EP, tarkin, Vader, and TFP.
magma was g7, the rest were g8. all level 7-8 abilities. Getting TFP as fast as possible with crit damage stacked on him was the key to 7* R2 for me. I would just restart if anyone other than Magma was stunned, ability blocked, or dead after their opening zerg. Beat it by focusing down R2 first other than killing Han with a single saber throw from vader. Leia was next priority, then Chewie, then Old Ben.
Vader lead didn't work at all for me, especially on tier 7 where they are immune to tm removal. Palp lead worked best.
Here's my empire: https://swgoh.gg/u/woodroward/collection/?f=empire
I've put TFP in t9 since then and taken the mods from them that I stole from my arena team to beat the event, but otherwise they are unchanged from when I got my R2 7*.