Assuming 1 Skill=1 mAcc still, this looks like the new goal debuff set taking into account the April update:
ItemSet 244320
Came to post this as the new debuff set. And yes it will be necessary on some mobs to cap out your gear.
I don't know why you are referring to Kurma as Genbu, that is confusing, just call the mobs by their real names. Furthermore Kurma resists a lot but finale and nocturne can be landed with just gear Macc. And, under the effect of Troubadour with 5/5 merits both will land rather successfully. Seeing as brd songs get dispelled often, you should be using N/T for debuffing on that mob.
The cure precast set should use an augmented genbu shield not a vivid strap especially since you main a sword.
Mdt set is missing Cthlonic Staff and can also be noted that Bokwus Slops and Lore gear are options.
Bokwus Boots should be listed in the song precast as being an alternative to Bard Slippers +2, Both pieces you should have anyway.
Also if an Iaso Mitra is in your potency set it should be in your precast set instead of Hyaline Hat since you have 4% occasionally quickens spellcasting from witful belt and veneficium.
ItemSet 300398
Genbu's Shield with 5% potency, 4% cure casting time, Iaso Mitra 10% Cure casting Time, Iaso Boots or Zenrith with 4% Potency 6% Cure casting time.
Will cap casting time/fast cast at 80%, potency at 50%, and have 6% chance of quick magic