I'd also argue that she was more menacing in the manga, she personally attacks (and defeats) the Guardians as early as in Act 6 and remains more proactive. In the anime, she does nothing until Sailor Moon meets her in the very last episode, where it's still Endymion doing the fighting while she stands around. She does fuse with Metalia but even then she doesn't get to do anything other than attack Sailor Moon and then die (can she even move in this form? it seems as if she's stuck in the flower she comes out of).
This. 90’s anime Beryl is really lazy by comparison and just sits on her ass all day probing her Crystal Ball.

(But to be fair to her, Demande and Galaxia are also really lazy bosses in the 90’s anime)
No, let's play a game. Look at just their debut episode up until episode 69. What was fleshed out or developed about them? Their four sisters who like make-up and fashion and Calvarez and Petz kind of have this dynamic of sibling rivalry as the two oldest and?
All their development happens in their redemption trilogy and then their swan song in episode 86. Until episode 70 we get no hint that Koan is an abusive relationship with Rubeus, until episode 71 we get no hint that Berthier feels bullied by her two older sisters and by episode 72 its just "time to redeem the last two"
They were more interesting as creepy occultist in the manga if severely underdeveloped and needed a random redemption arc to be interesting in the anime. And look Koan's breakdown was one of my favorite moments in Sailor Moon but that doesn't change things for how they were before episode 70.
They had very distinct personalities though, they weren’t
just makeup and fashion obsessed vapid air-heads even before their respective redemption episodes, I feel like that’s a hyperbolic flanderization of their actual personalities.
Koan, as the baby of the group is shown to be naive and impulsive but really earnest with a hot-tempered passionate side.
Berthier plays herself off as the unassuming ditzy airhead but is actually really cunning and ruthless.
Calaveras is a sarcastic, charming and ambitious diva type who likes to poke at Petz to get under her skin but really does seem to care about her, and more often then not her jabs seem like a misguided attempt to help Petz see the light and learn how to let go and depend on her more. She seems to be the “common sense” one of the group who frequently likes tells it like it is and keep it real for the group.
Petz is the no-nonsense uptight one with
alot of haughty pride and anger management issues that can’t stand being shown up - she’s the one I would argue is the most developed of the Sisters and goes through a whole character arc from her very debut (not just in her respective redemption episodes) It’s clear she has issues with teamwork and looking vulnerable as well as leaning on others for help - life seems to be a constant power struggle for her which she learns to let go of by the time of her redemption. We also get hints of her messy history with Saphir from her grudge against men that is referenced several times in her fights with Calaveras - she actually helps to serve as the perfect foil to Makoto.
So no, I think it’s inaccurate to say the Sisters were shallow characters from the start
until their redemption episodes. Like it or not both they as well as Ail & En are who fans often cite when they note the excellent villains of R - they’re some of the most memorable characters and for good reason I’d say! (The Sisters also have the honor of being the first miniboss squad who were
all redeemed - something that wouldn’t happen again until SuperS with the Trio and Quartet)
Esmeraude is fun but she’s who I would actually characterize as a shallow villain, not the Sisters.
I have my own biases for both Demande and Saphir, but objectively speaking the Sisters
are better developed characters than them - they simply don’t get enough screentime to really shine.
Rubeus and Black Lady are both better done in the Manga/Crystal.
And Wiseman… Well, no one actually ever
really cares about the designated “ultimate Eldritch bad” of the season. (He
is very effective at getting you to hate him for villainy though, more than any other of the Eldridtch Energy blobs in the series I’d say - garbage, nonexistent lore compared to his manga counterpart though)
Both Ail/En
and the Ayakashi Sisters are who people usually first think of when they cite R as being known for it’s standout villains. The others are either badly written and devoid of personality (Rubeus), Shallow Characterization (Esmeraude and Black Lady) or underdeveloped with not enough screentime (Demande and Saphir)
But the problem is when you flesh out the underlings, their bosses have to be made made more nasty to compensate to emphasize that these people are bad. If everyone has a tragic backstory or is sympathetic, it takes away from any rooting interest.
But if that’s the case why were Tomoe, Nehellenia and Demande made more sympathetic then?
Besides, even if you did flesh him out, the fact is he directly tried to kill a kid and ordered other people to kill a kid; there's no redemption from that.
And Demande tried to sexually assault a 14 year old and he
still managed to get redeemed and be portrayed as sympathetic - I guess Toei’s mind at the time was that SA was “less bad” than attempted child murder?
Galaxia is a completely different case. Given how short that Stars season is, it's pretty clear those making it were caught between overtaking the manga and finishing up the story with the episode count, but at this point, the formula had become the standard (even though the Nehelennia arc which bent the formula is widely regarded as superior). Galaxia wasn't made into a flat villain because because she was a bad boss, but because they didn't have time to do anything with her and they had to create an ending from their own take on the material...and it shows. It doesn't help that of all the arcs, Stars is the one that had to stretch the most to fit the MOTW mold to the point where it's easily the least similiar the the cosmic scope of the manga. For Galaxia, it seemed like the format and setting changes themselves flattened her rather than them deliberately making her one-dimensional to be hated.
Would you agree that the season’s decision to hyper-focus on the budding SeiUsa “romance” to the determent of everything else was also a contributing factor in Galaxia’s characterization downgrade?