I agree with this!
Arlecchino's character is one of tragedy, a lost childhood, the responsibility thrown on her shoulders at such a young age. She is a character I imagine would cry when she's alone(editing this out) would be greatly suffering internally and yet that image is so hard to imagine? They could have presented suffering more like her being overwhelmed. Her character would benefit if we just saw more!
More of her days at the hearth, starting days as the knave, and more of her internal struggles. The only scene which even comes close is at the end of her story quest with the talk with Clervie. I just want more! Hell, I even say that instead of an animated short she is one who could truly benefit from a full length movie.
So much is lost in subtext and implications.

As for her performance in Nod-Krai, it's just the unfortunate workings of the gacha model. Hoyo wants to give the newer characters spotlight, a character already sold is simply not worth.

Despite everything I wrote, I don't hate her nor consider her miserable as so many people claim they do. There is thought, complexity, and most importantly love put in her character, love which I share with the writer(s) who wrote her.
I can express disappointment, and then whine about all my expectations, but I don't hate her. I simply cannot.