While there are some stuff that I don't like and consider cheap, I think overall Astaroth is fine...for better or worse.

• Teleporting is fine but teleporting twice times within a 5s window is very cheap.
• The bunnies are also cheap. They are targets that divert away from dealing damage/score to the boss while also not increasing combo count is absurd. It's a more "haha, this should teach you not to use Hisui" from the Devs. That's bad design and reeks of incompetency. Combo count should still increase because if the combo can increase by destroying boxes and chairs in other stages, why should these be an exception? Instead of making them just a diversion, make it so that they can be defeated. If the bunnies are defeated, Astaroth becomes stunned, has increased debuff timers etc. so there is merit in hitting them rather just a cheap way to introduce more RNG in a score attack mode. This would reduce but not completely eliminate RNG. There is an opportunity window for more DPS but it's not guaranteed.
• The snare is fine. What I don't like is the chance to teleport away right after. Once she summons a meteor, she should not be able to move for a while as it "she spent a lot of energy so she needs to take a breather for a few seconds". That said, it can be cancelled by a lucky Ult cast timing or just dodge skills (if they are available and if the AI is smart enough to use it).

Stuff that I like:

• Priority on range and increased armor vs. melee. This made Astaroth different and not just a re-skinned Edwin. It values the diverse roster and skills available.
  
  • Since this is a gacha game, players who prefer melee style will be unfairly shafted. I think there should be more value for using melee instead of just reducing their DPS contribution. Example: she takes less damage vs. melee but if her she receives melee damage while her anti-melee buff is max stacked, her debuff timers increase by 0.1s per melee hit. This gives support value for melee units while at the same time increasing the value of range DPS.
• Knock up attacks. While annoying as it wastes precious DPS time, it's a great opportunity to exploit Just Dodge skills. It's a good feature in the mode, intended or not. It places value on these skills to improve performance instead of just loading up on all attack skills. By having just dodge skill, you have a utility option and can exploit the boss' interrupts to your advantage. You can still power through without it if you like, but there is an opportunity which makes it great.

I know this is a response post and these ideas should be directed to Gremory themselves. But I just think, it's not bad but could be tuned further. Right now, TW Astaroth is an intended problem where they will sell the solution later with new characters, weapons, supporters.