To clarify, a Scholar would only receive Aetherflow for the fairy abilities that HAVENT been used. So if you used Dissipation but Whispering Dawn was not on cool down you would get an Aether Stack. This proposed Dissipation isnt for getting Aether Stacks. Its meant to be used immediately after blowing through your fairy abilities so you would ideally use Whispering Dawn and Fey Illumination together and then Dissipate your fairy so that you can resummon Eos with all her abilities reset with 10 seconds to spare before Whispering Dawn has ended. You dont need additional Aether Stacks or more potent healing if you use this skill correctly.
This trait may seem useless but objectively it is because the SCH skill set is already numerically balanced to handle small pulls in dungeons. Physick would only grow in situations that demand it like when a tank pulls a mob so large you blow through lustrates and are forced to alternate Adlo and Physick or during long end game encounters where mana efficiency is more important. This trait isnt meant to break healer balance but give the Scholar an effective answer to the cost imbalance of Adlo and Succor during the encounters where it counts most. Summoners are also the only DPS with a reliable heal that can be spammed and this allows them to grow more effective if a healer dies and they are the only source of healing for the party. It isnt meant to overwhelm game balance for Summoners or Scholars in normal content. WHM and AST have Cure2 and Benefic2 they can spam and this would help Physick bridge the gap in crisis.
Selene will still prioritize the lowest target so spamming her Caress will default to a posioned person once their health drops sufficiently if other debuffs are also on the party. Selene is only used when less healing is necessary in the first place though so giving her a reduced potency shouldn't matter. Her ability to raise and cleanse makes her a true support because the Scholar wont waste the MP or time required to do these tasks. It means Swift Cast can be used for healing and not rezzing. For a Healer I think this would be the perfect support pet.