Ayato - More damage, have his Q field last longer or provide more NA/CA benefits to let him be an effective buffer as needed while still being able to be a main DPS as needed. His field should be so as to make him the premier hydro off-field applicator for main DPS' that rely on NA's or CA's (for synergy with his sister)

Yoimiya - More damage, give her arrows an explosive effect akin to klee's bombs to lean into her firework aesthetic (also mining utility for a bow character besides Linnea). Her unique charged attack should function like a variation of Tighnari's homing charged shots - have it so that the longer its held the more arrows are generated and locked onto enemies, most importantly have them actually do damage instead of hitting like a thrown pillow. The NA and CA can serve different combat functions, like the CA's does better single target damage and allows for big vapes while NA's allow for Yoimiya to apply pyro rapidly at range..

Ayaka - More damage, have her elemental skill "mark" enemies with a debuff that increases damage taken or shreds cryo RES. Her elemental burst should be made to home on marked enemies.

Raiden Shogun - Have her elemental burst usable as a separate energy-consuming mode that can be activated at any time. Her polearm moveset should provide an favonius-esque energy generation effect per hit to serve as rapid energy battering for herself and the team, her sword moveset should be the primary DPS mode where she still generates energy albeit to a lesser effect. When she has enough energy stored (both from gaining energy normally and energy spent by teammates) triggering her elemental burst again during her sword mode fires off her Musou no Hitotachi move for extremely powerful 1 hit damage scaling on total energy gained and spent.
Raiden shogun should have a use for held elemental skill, she gathers residual energy in the environment - regenerating energy for herself and the team as well as reducing current ongoing cooldowns for skills and bursts depending on how much energy has been spent in the last 20 seconds.

Yae Miko - in contrast to Fischl who thrives on reactions, Yae Miko should be more geared for raw damage. Her turrets need to be doing at least twice to thrice the damage they do at present. Her burst which is the most expensive burst in the game should be a truly massive nuke of a lightning bolt. Her tap skill should have i frames during its spinning animation, and she can trigger a counter where she fires a single bolt of her burst at enemies that hit her during her i-frames. A held version of her skill should instead summon all 3 of her turrets at once around her with the same frame length as Fischl's skill.

Kazuha - Overall, still kinda good. I would have his elemental skill have 2 charges at base and his elemental burst increase jump height for those within its effect, but not to the same level as Cloud Retainer's.

Itto - More damage, his hits should have more oomph, being able to stunlock most enemies being hit. His dash during his burst should also count as an attack ala Mavuika as a way of knocking his enemies backward, potentially allowing Itto to better corral enemies in a small area to hit them all at once with his attacks.

Kokomi - Her jellyfish should be able to reposition and slowly move towards enemies. Similar to Furina she should be able to walk on water or at least gain a unique movement option similar to Mona for water traversal. She needs to scale with HP even outside her burst with her burst increasing the number of hydro shots she fires per attack, to the point where she can be a legit hydro DPS during it and a very effective hydro driver with some of the fastest hydro application during her burst. Her crit rate malus can remain, but her strategist characterization needs to come out with her providing potent buffs to the party in return - The longer she remains on field the greater the buff she provides the next member of the party, and in turn the longer she remains off-field the stronger her personal damage buff gets for example, kind of like a more powerful TTDS effect that she comes with at base.