Hot take: I agree that Hoyo wants Arlecchino to have less friction and is making unnecessary adjustments, but people still underestimate how brave and strong Furina is (6.7 event spoilers)
This is a lengthy post, but I want to gather all of my thoughts and try to express them as best I can. I understand that many people may disagree with me, which is absolutely valid. As I am sure many people are aware, Furina gets to play a part in the new event, which is wonderful, and towards the end she attends a tea party with the Traveler, Sandrone, Columbina, and Arlecchino. During the tea party, she seems relaxed and has a good time, which has upset some Furina enjoyers due to the unpleasant history Arlecchino and Furina share
I personally agree that it feels like Hoyo wants characters to get along better, even when it doesn't make much sense, and I also agree that it's a genuine shame. I feel like if there was tension or outright dislike between more characters, it makes the characters feel more genuine (since relationships, trauma, and grudges can all get very messy with real people)
Case and point being Arlecchino. Many people have pointed out that Arlecchino on release in 4.6 didn't seem fond of Sandrone, commenting on how she keeps to herself and is more occupied with machinery, but seems to have a positive relationship in Nod Krai and in Sandrone's animated short "The Final Gift".
You could argue that in Arlecchino's first voiceline about Sandrone that she was being deliberately duplicitous since in character she mentions she doesn't mind when people have misconceptions about her, and that pretending to dislike Sandrone was just a way of keeping her cards close to her chest. However, they just added a voiceline for Arlecchino about how her opinion on Sandrone has changed and that she sees her in a more positive light since Nod Krai
Now, if you could argue that Arlecchino's happiness in "The Final Gift" at the tea party is moreso due to having a chance to spend time with La Signora or even Columbina, and that Sandrone was just kind of there by extension, but I do feel like that's a bit of a stretch. The point of this post is moreso to talk about Furina, but I wanted to give my thoughts on Arlecchino's character to give better context
While I do feel that the tea party did go smoother than I would have liked, and a little more tension would have made the characters feel more alive, I also believe that having Furina run off crying or completely shut down from fear would be a betrayal of her character; namely her incredible amount of courage.
When people talk about Furina and Arlecchino, they like to point at Furina's voiceline, but I think people might be misinterpreting what Furina says. Her exact voiceline is
"The Knave? W-Who's that? Oh... Uh, I'd already forgotten about her... Keeping such a terrible figure like her in your mind will only give you nightmares."
Some interpret this to mean "I have nightmares anytime Arlecchino crosses my mind, and I am deathly afraid of her to this day". My personal interpretation is that she is commenting on how she doesn't like dwelling on her encounter with the Knave, and that Arlecchino in general is an intimidating person.
My main support for this interpretation is Furina's own conduct during 4.1. People often forget that Arlecchino attacked Furina BEFORE either of their two tea parties. Neuvilette himself also tells Furina they can just ignore Arlecchino's request for a meeting at the start of 4.1, but she chooses to meet with her to take accountability for what happened to Childe.
If Furina was genuinely traumatized for life, I don't see why she would agree to such a meeting, when Neuvillete himself says it's not necessary. What's more, she agrees to have a SECOND tea party with Arlecchino at the end of 4.1, and when she is accused of inaction and being irresponsible as the Archon, she stands up to The Knave.
My takeaway from Furina agreeing to not one, but TWO tea parties with Arlecchino even after being attacked is that Furina's sense of justice and courage far outweight any terror that had been inflicted on her. This is not to say it wasn't a horrifying experience to be attacked like she was, but I feel that if Furina was deathly afraid of Arleechino she wouldn't have agreed to those meetings and she certainly wouldn't have had the courage to stand up for herself when scrutinized.
Now, all of that was way back in 4.1. Since then, the two haven't appeared on screen together, but we have gotten Arlecchino's voiceline in 4.6 About Furina. She expresses no disrespect nor disdain for Furina, and comments that she has people from the House of the Hearth send her desserts. While I am sure just about everyone would agree that cakes do not make up for attacking Furina unprovoked, I also feel that Furina isn't the type to hold grudges or resentment, and that she would likely just enjoy the desserts for what they are.
Between her own courage in 4.1, being used to getting desserts from Arlecchino, and most of all having time to heal, I think it's honestly within reason for Furina to enjoy having tea and treats with Arlecchino since other people she trusts and likes are also present. I personally would have liked a moment of hesitation, maybe a second of freezing up, or a bit of uncertainty in her tone, but I think Furina having a good time is okay. I'm glad she got to have a good time with this festival, and I hope we get more Furina screen time in the future
TLDR: Furina is very brave for meeting with the Knave twice and I don't think she's as traumatized as people believe. Between that, having time to heal, and being in the company of others that she does trust and like, I think Furina enjoying her tea time with the Knave present is okay. I do agree it's a bit forced though and would have liked a little more tension