Disney Dangers

Please take this as historical context and constructive criticism.

Beauty & the Beast has been made 3 times- 1946, 1991 & 2017.
The original movie was directed by Jean Cocteau.

He was a poet, novelist, painter, playwright, set designer, and actor in addition to directing. He was also openly gay, and his lover Jean Marais played the role of The Beast in 1946. The metaphor used in the original film is not subtle- it portrays male sexuality as potentially quite dangerous. The original fable has a strong theme of anxiety a woman faces a she grows to maturity and into the world of adult intimacy-- Labyrinth (1986) heavily examines that same theme (deal with it).
Here is a good overview of a much longer book examining the first 2 films. It's a good synopsis of the points I'm poorly making.
Cocteau & Disney
Some trivia from that article, Cocteau suffered from a horrible skin condition while directing the film, giving him a horrific visage.
I find it interesting this movie was made years before Ben-Hur (1959) & Spartacus (1960). In the Hollywood of the 50's & 60's, the homosexual topics & subtext such as that of these two films was so well concealed, even the actors weren't actually aware of it. The contrast is striking.

The 1991 film was scored by Alan Menken with lyrics by Howard Ashman. Ashman wrote lyrics for a number of works including Little Shop of Horrors (1986), The Little Mermaid (1989), Beauty & the Beast (1991) and even Aladdin (1992). He won the Academy Award in 1991 for the title song "Beauty and the Beast", posthumously. He shared with Menken in 1988 during production of Little Mermaid that he had contracted AIDS. Animators traveled to work with Ashman in his home because he was too sick to travel and work. He died before the 1991 release of the movie he poured his last life into. It is majorly because of Ashman's talents and influence that Disney makes musical films at all-- Mermaid was their first in 30 years. Many believe that the Beast's curse in 1991 film is a metaphor for Ashman's own curse, the disease that took him.
Ashman & Beast
Related, Little Mermaid is about being born in the wrong body, and changing for a guy who never noticed you (deal with it).

The 2017 film was directed by Bill Condon, who is openly gay. I haven't seen it, and there seems relatively little tragic about it.

All of this is to say, tap the brakes on this adventure. You don't actually have to change anything from the movie plot (any of them). The beast is definitely a villain- he is a character from a simpler time when audience could tell visually that a villain was bad--
A villain has a villainous mustache,

wears a black hat,

was moorish,

or a dwarf.

The challenge of the beast was to confront your assumptions. By now, the antihero, or the redeemable villain, is a common trope-- we are always expecting villains to have some hidden heart of gold these days. As I understand, the Beast character in fable isn't perfect- he did get cursed for cause. But he's not as bad as Gaston, because let's be clear, 1991 Gaston is a likely rapist. Belle wasn't into him.
I really have to disagree that any other Disney story has Gaston as the hero-- most Disney heroes are young women with narratively disappeared mothers. I don't think he needs to be made a hero here, either. In most versions, he's an antagonist, but not a villain. He is in conflict with the Beast but whose motives are better?

If I had to change it just a little, I would have Belle's father implore the PCs to a rescue. Gaston could accompany as a concerned NPC, maybe a mountain guide, but urge them towards the more violent solutions. It's always a possibility the PCs would miss the source material entirely because haunted constructs are something many PCs would just attack. Pity the poor crockery they smash (it might be Angela Lansbury!).
If Gaston is urging them to crash the gate to the beast castle, you could explore one of my favorite subjects-- why do PCs feel entitled to just role into any random castle and start breaking down doors? Suppose the castle inhabitants have been waiting for the curse to break, and the beast is really doing penance. If none of the constructs can talk or communicate, they would have to attack the PCs as any dangerous intruder. The Beast would respond likewise to criminals invading their home.
I think what I am imagining here is tricking the PCs by happenstance into being antagonists, maybe villains. That is always a fun reversal to play on the PCs, to make them into part of the mob and reveal later they may be on the wrong side. Maybe the entire adventure leads to a moral choice, where the PCs can side with the Beast & Belle or with Gaston, knowing all they learned passing through the castle. The fight would of course be between whichever was decided to be the villain, and Gaston has learned all the party tactics... Maybe he depleted PC resources to kill everyone and take his 'love' with no witnesses...

Beast can be extremely evil, depending how much detail or backstory you make up for the Baron, but Belle might still choose him. Gaston represents the male sexuality I mentioned way back at the start of this essay-- Gaston takes all he wants. The PCs may decide it's best to return Belle to her father and dispatch the Beast but Gaston isn't wholesome, considering he just got the PCs to smash a castle full of peasants. If Gaston knew the state of the castle inhabitants, that they were the furniture because of his travels into the mountains, then he definitely contrived to have the PCs massacre a lot of people. Not heroic. One last twist, if the Beast goes Beast-mode and does tear apart Gaston (maybe after he has surrendered) because of his obvious danger, that might push Belle to leave him as well. Not all Beasts have a heart of gold- there are real monsters in the world.

I would just ask you don't use Stockholm syndrome. It takes away agency from the character of Belle who is described, in 1991 film, as "strange," "funny," "peculiar," "odd," "very different from the rest of us." If you really want a really good version of Beauty and the Beast that is about horrors of Stockholm syndrome it would be called Phantom of the Opera. There is a lot of examination and color you can do trough the eyes of PCs and still use all the same story beats as the film. Disney is all about smoothing over the rough edges of very messy fables, and I think towards those rough corners is the best direction for your adventure.