tbh isnt hardmode suposed to be HARD... learn 2 interrupt ,)
Honestly it isn't even about the interrupt, it is about the RNG involved and the reaction time.
You have no idea when Revan will do force lighting, all you know its that he will do it after his first force storm. Since the defensive CDs are only active for a couple seconds, you really have no idea when it is a good idea to pop it other than taking an arbitary (35%) for us and then hope for the best.
If you do survive the first tick of lighting, that is great. You better hope that someone hit that interrupt the moment he/she see a cast bar Revan. Cuz if no one caught that, the next tick will kill the tank and then Revan will switch and immediately kill the next.. and the person after that.
Even if you do manage interrupt it, you better hope there is a 2nd person with an interrupt active for when Revan recast his Force lighting 4 seconds later. Since no one can survive the first tick, Revan will bring someone down before his 2nd cast gets interrupted.
Then if your DPS is good enough, you will bring him to the metor phase and for the rest of the fight is seeing if you can burn him down fast enough to 5% and then can all stop DPS so he doesn't bug out and kill people with the bubble on him.