Honestly, the only problem with Aetherflow in its current state is its ties to the Fairy Gauge.

Returning Energy Drain to SCH would be weird for Summoners, since they no longer have Aetherflow as an action. A better solution is to make holding stacks of Aetherflow beneficial.
So rather than give back Energy Drain (MP is a real non issue in my experience) why not have it give Fairy Gauge at a steady rate, modified by current Aetherflow stacks for as long as we have at least 1 Aetherflow stack?
Something like 1 Fairy Gauge per 2 seconds, per Aetherflow charge we currently hold.

Also would love to see a new spell for the Fairy that allows us to consume portions of the Fairy Gauge to reduce active cooldowns by 10~20 seconds.
Its something to spend Gauge on that isn't Healing or Damage (the moment we get Damage spenders for AF or FG, that'll becomes the meta thing all SCHs will be demanded to do) but benefits the Party through more Chain Strategem, more Recitation and being able to dump Gauge into getting Seraph back quicker.