I don't raid on NIN, but I do play it on occasion. I still don't like Forked/Fleeting since it completely changes our relationship with Trick and Raiton. I makes it difficult to fit all of those skills into a TA window. It's very annoying that it procs off of every Raiton cast, including the one in TCJ, which further compounds this issue. It feels like to me that NINs rotation completely changes at 90 instead of building off of what was already established. So, my proposal is thus:

Have Fleeting Raiju be an Enhanced Kassatsu ability. (Enhanced Kassatsu II)

With Enhanced Kassatsu II, Kassatsu's effect is changed to this: While under the effect of Kassastsu, "Ten" is changed to "Gokka Mekkyaku", "Chi" is changed to "Fleeting Raiju", and "Jin" is changed to "Hyosho Ranryu" while granting two stacks of Kassatsu. Executing "Gokka Mekkyaku," "Fleeting Raiju," and "Hyosho Ranryu", will consume one stack of "Kassatsu" as well as preventing that same Ninjutsu cast. (Duration: 30s)

Fleeting Raiju would change to an AoE with damage fall off so that it's used in either AoE or single-target. Then you have the option of using Gokka or Ranryu depending on the amount of targets.

I would changed Forked Raiju to an Ability, doesn't gap close, and is only executed under the effect of "Enhanced Meisui" (bringing the level it's learned at lower). Enhanced Meisui boosting Bhavachakra reduces the effectiveness of Fuma/Ka/Sui in AoE, assuming you already have a Doton out.

And one more change I want: Shukiko III affects Death Blossom and Hakke Mujinsatsu instead of Aeolian/Armor Crush. Ninja is generating too much Ninki in single-target while not generating nearly enough in AoE, which is especially baffling since Hollow Nozuchi can proc off of Hellfrog Medium casts. Ninja feels very feast-or-famine in single-target vs AoE.