Okay, so we talk about balance and character design a lot, but an important thing to remember is that the characters don't all need to be balanced against each other as long as all of them are giving a fun cohesive play experience. I'm going to run through all the Myth girls and what I think their intended playstyle is, and talk about what in their kit, if anything is contradicting the rest of their abilities just because I'm bored and think about shit like this all the time anyway.
>Ame
First of all, she's clearly meant to be the most basic character, that's why she's the default character your cursor starts on and it's why she has the skills that are literally just "damage up", "crit rate up" and "get a companion".
She functions perfectly in the capacity as the basic tutorial character that scales well with basically any normal playstyle for basically all modes. Even her special being both a slow all enemies for use as a panic button and a massive attack speed steroid for deleting scary waves or strong enemies fills every intuitive roll that a player would think to use a special in under most circumstances.
She doesn't need any changes at all because she's not supposed to be the best character at anything, she's supposed to be simple and reliable, and she is.
>Gura
Gura is super obviously supposed to be the character that teaches you taking damage isn't the end of the world if you're built to do it. An introduction to the concept of tank characters, the only problem here is that dodges are not a "level 1" tank mechanic. Irys is better as an introductory tank than Gura which shows in which one of them is better at it.
That said her entire kit is built and driven around "stack em up and mow em down" braindead recklessness. It's perfect and I wouldn't change anything about it, it's just unfortunate that evasion is the most obvious way to make Gura a tank thematically.
>Ina
Ina is a more technical character than the others, the actual design of her kit is built around amassing a cult and having it follow you to maintain a big damage boost. Having a means to "cash in" your damage boost for healing by touching the takos is also good. It introduces the player to the concept they use a lot in these reverse bullet hells of "clustering" enemies into a big pile to kill them more efficiently. Which is also what her special is for.
The problems with Ina are mechanical stuff that's super unintuitive. I think Tako probably need to give xp back when touched so she's not crippled on her leveling, but they shouldn't count as kills, and they shouldn't proc effects for contacting enemies. The latter actively feels like a bug.
>Kiara
Kiara is the only one of the Myth characters that is actually conflicted in her design. She's trying to be two characters, one centered on movement, and another centered on perfect play. It's a fairly easy fix to turn her into one or the other, but her being a hybrid as one of the five starting characters doesn't feel right.
I think she's intended to be the movement character due to the fact two of her three skills are related to movement, and the shield was just the solution Kay came up with for allowing her to occasionally run through enemies to maintain stacks of dancer. There's a couple better solutions though, make it clear that it's supposed to be used more often, rather than trying to preserve it, make it so that it's cooldown based instead of a reward for not taking damage, make it so you're actively encouraged to charge through enemy lines with it because it deals damage or something, anything to emphasize the theme of "constant movement" over avoiding damage.
Her ultimate is also lazily designed, it's very pretty but it's just a damage nuke with a lingering aura, when she's not a character that needs a damage nuke based on her intended playstyle. I think Kiara perhaps more than anyone else has been beaten up by future content. Her potential revive mechanic probably being cannibalized for Ollie.
Finally the most obvious thing is that dancer just sucks to play, it's the most punishing skill in the game by a massive margin, and it should definitely fall off incrementally.
>Calli
Calli as she is post rework is fine. Initially she was a character that seemed almost designed to introduce the concept of deadzones, but the reward for playing her well was just not worthwhile. Now post rework she serves as the character that teaches you to actively run down enemies, as she should because of her theme.
All of her kit rewards you for staying close to enemies and actively trying to kill them for benefits, always making sure to keep enemies in the range of her weapons, with an ultimate that's not useful as a panic button to encourage you to use it to quickly wipe out bosses and farm waves.
She's a less interesting character post rework, but she's also a much better starting roster character, and a lot more fun.
I think this is absolutely one of the two directions her you could have taken her.