Quick and easy response to Empen being limited: Use 1 Snowl
The biggest reason Snowl wasn't as popular before the banlist was cost. UR materials are always scarce making the case for an SR rarity floodgate extrememly one sided. Snowl is an incredible card that anyone who has used it before will tell you how hilariously it changes the tide of battle. Think of snowl as a book of eclipse or book of moon in monster form. While also acting as a bridge for chain blocking. If that wasn't enough to convince you to spend the materials to craft it can even give all your monsters piercing damage.
There are many different ways to build a Floow deck so feel free to swap in some of the cards I placed in side deck for suggestions. I personally wouldn't use pot of desires although it can give you access to floow names. Just make sure you have a winged beast in hand before using pot of desires to normal summon giving access to the banished floow monsters.
If you want to use harpie feather storm I would suggest considering more harpie monsters such as:
Harpie Perfumer (Searches Feather Storm)
Harpie Harpist (Can bounce an opponent's monster or search a Winged Beast)
Harpie Dancer (Can let you summon Raiza an extra time. Even better with Simorgh Field Spell or Unexplored Winds)