"Another theoretical path for Zoe would be to let Chloe redeem Zoe. We know that Zoe was a massive liar in the past."
If I understood your pov about a Chloe redemption and how Lilia neither has reason to be on the show: if you had to use a character for Chloe to redeem, and kinda serve both as a foil for her and a lesson for Adrien's character growth, it wouldn't be Zoe, but Lila?
*sighs* You bring so many good points on the characters' writing that I can't beleive how many "repeated" characters the show has! Would you consider Socqueline another innecessary character?
(Post this was in reference to for Zoe and for Lila)
It's not shocking that the show has "repeated" characters. It's a school drama with 21 teen heroes in the canon cast (24 if we count the special characters). It's damn near impossible to give that many characters a unique role in the story unless you're dealing with extremely complex plots a la Game of Thrones where it's less one large cast in a single story and more smaller casts in mini stories that all intermingle. If you look at something like GoT, you'll notice that, while the overall cast is massive, each mini story has a more normal sized cast and those smaller groups only come together after they're extremely well established. Miraculous could have done something like that with each member of the class getting a mini arc that focused on them, but it didn't, so the cast is basically a uniform blob.
Before we talk about Socqueline, I wanted to quickly make some comments on Zoe and Lila. If I had to have Chloe redeem someone to show off her new skills post redemption, then I'd have it be Sabrina. If Sabrina is off the table, then I'd pick Zoe. If Zoe is off the table, only then would I look to Lila because why use Lila when you have Chloe's best friend and sister as options? That's far more compelling than some random girl no one knew before this year and who no one is connected to. Even the Zoe route is questionable since she's so underdeveloped right now. Both her and Lila would need major work to be fully functional characters and I personally have no interest in doing that work since I don't feel like it adds enough value to canon.
I will note that Lila and Zoe actually had potential to be an interesting contrast to each other since they're both liars. Redeeming one and damning the other works far better than doing the same narrative with Lila and Chloe since Lila and Zoe have the same core problem while Lila and Chloe have nothing in common to the point where canon has to retcon in Chloe having a Marinette obsession so that the Chloe and Lila team up made sense.
Similarly, if you damn Chloe, redeeming Zoe could have been interesting. You could even redeem her and then, though her, save Chloe since Zoe hasn't suffered from Chloe anywhere near as much as the rest of the cast. That and their sibling status makes Zoe a decent choice for the person who changes Chloe's heart just like the Zoe's backstory feels like a good contrast to Chloe's canon story.
Zoe is introduced right after Chloe supposedly proved she didn't want to change (for this post, we're pretending people actually tried to help Chloe and failed). That should mean that everyone is really freaking wary of the new girl who shows manipulative tendencies while also claiming that she wants to change. That could have led to an arc showing how you know when someone does want to change and how to navigate that.
I don't think Zoe is a great candidate for that since she's a total stranger who no one but Chloe has any reason to care about, but it would have done something to make the people in canon actually learn the supposed redemption lesson we're currently missing. As-is, Marinette just randomly believes in Zoe right from the start and Zoe is good basically right from the start, showing that Chloe's betrayal meant nothing to the cast and driving home that Marinette's first impressions of people are basically always right. Adrien seems to be the only exception.
Socqueline is a totally pointless character who I would never have included. It's not that she's bad in and of herself, it's that she once again adds nothing to the cast that wasn't already there. She is Origins Alya on steroids. She's here to protect Marinette from Chloe and inspire Marinette to be brave and that's about it. Why she needed to do that when Alya is supposed to have that role is anyone's guess.
If anything, Socqueline undermines Alya since we now know that Marinette had an amazing best friend before Alya came around! Socqueline was willing to fight Chloe even before Chloe randomly mellowed out into a nicer person because seasons one-to-three Chloe has nothing on Derision Chloe. Even seasons four and five Chloe aren't as bad as Derision Chloe. This show has no idea what it's doing.