I run a very similar deck in platinum ranks at the moment, hopefully should get KOG if I have more time to play tomorrow. I'd recommend losing Twister, it's just often an unnecessary card alongside HHG. I'll cosign on a continuous spell like shard of greed or card trader (especially to send HL Sisters back to your deck), and also even Wonder Ballons which synergizes with Quill Pen.
1.) Remove Twister (you already have Harpies to do the Removal of Spell/Trap) + twister only destroys face-up spell/trap and it adds 1 card you don't need.
2.) Remove 2-Skull Red Bird and 1-harpie lady(normal) replace with harpie lady 2 or 3 (if you want to negate flip effects like lady bug or if you want to delay a monster for 2 turns, this way you can summon more harpies/twister.
3.) Replace those cards with Riryoku or Enemy Controller. E.Cont is like having a second Kuribo(if u don't have 2 in ur deck), Riryoku so you can beat down monsters that has higher ATK than Harpie Sisters. (But Union Attack is Best if you got it from Yugi Muto).
People always run spell-remove cards...
so keep 1 or 2 independant spell-remove
Nobleman of extermination + twister... or de-spell + tornado wild.
remove the red birds.. remove 1 Elegant egotist
i like to keep only 1 sisters to not get hand-dead.. so you're in the way
Enemy controller is your friend... 2 of it
the new trap is a good trap.. +1.500 atk, could save you from atk and let you finish nxt
Do whatever u want. This deck heavily relies on the field card and is screwed if opponent draws despell first turn. That's why most people run a hybrid harpies deck