OK, I'm digging deep into my brain now, gotta give it all, since Kallelinski is doing so much work already.
1. Geralt is deciding how to comfort upset Ciri, after Vesemir's death, I've had some ideas for alternate ways to handle this, with Yen included.
If Geralt says "Relax, you don't have to be good at everything.", instead of current depressing scene, something like this goes:
When Geralt and Ciri sit down to get drunk, Eskel and Lambert could've joined in, true to their Kaer Morhen custom, and turn glum atmosphere into a bright one. They could reminisce of good times with Vesemir and cheer Ciri up, while at the same time processing Vesemir's passing like adults.
After they've had a few, Lambert pulls out Vesemir's hat, puts it on Ciri's head and exclaims due to recent vacancy, it's time to make Ciri an official witcher/witcheress. Everyone else toasts to the best idea of the evening and they all drag their drunken asses across the lake, to the elemental stone shrine (where Geralt went with Lambert before), on the way fighting the trolls in their drunken state.
That scene ends with Ciri and Geralt sitting together, staring in to the mountains and both proclaiming they miss Vesemir.
In the morning, Yennefer and Avallac'h find them passed out on the site, with Lambert sleeping on top of Eskel, and Ciri on top of Geralt. Yen's shaking her head at Geralt, while wrapping a blanket around Ciri and hugging her.
Avallac'h offers a snarky remark "It's amazing you humans survived at all, let alone rule this word...", as the camera zooms out to show the elemental stone shrine with Vesemir's hat on it.
If Geralt says "I know what might cheer you up", leave the snowball scene exactly as it is, but implement a moment to show Yennefer looking at the approvingly and lovingly from the window, maybe even cheering for Ciri.
***
4. You have to let Ciri ransack Avallac'h's laboratory, my alternative way to handle it.
There is a multiple consistency and lore breakdown here. Ciri is portrayed like a vulnerable teenager, susceptible to the venom mean girls in her class are spreading. That Ann Elle woman is a stranger, means noting to Ciri and is obviously jealous/buthurt about Avallac'h spending so much time with her.
The character the Ciri is, someone who's been beaten down and abused since early age, someone who's found an incredible fire during her teen years with the "Rats", there is no way in her she'd just stand there and take it.
She would've exploded in a storm of anger, venom and malice doubled to that of the elven woman. She would let her have it and then some and maybe even headbutt her or fake to make her jump in fear.
She would've shown that she is the daughter of Yennefer, the iciest, stormy bitch when provoked.
Of this temperament we have proof from CDPR themselves, in Ciri's solo encounter with the Lodge, where she made Philippa Eilhart go pale.
Now, if CDPR would ever decide to adjust this, there is actually room for two decisions to be made here by Geralt, and a HUGE missed opportunity.
Choice number one: As the elven woman is nearing the end of her nasty speech, Ciri is looking at her and then at Geralt, her expression "is this bitch for real?"
Now players can decide if Geralt steps forward to defend Ciri, or takes a ceremonial bow, like he was thought by the Nilfgaardian butler (to Yen's amusement), and let Ciri have at her.
As Ciri is verbally obliterating the elf, Yen is visibly angry and in a boxer's stance, her fists punching the air and whispering loudly (to Geralt's amusement):
"Hoo! Good, Ciri, good! Now work the body, work the body! Under the ribs! Under the ribs!"
Choice number two: After they've dealt with the elven woman, I can only then understand CDPR's reasoning that Ciri would still be upset, that their racial profiling still gets to her, after all this time.
Now, we get to decide whether to ransack the place to let off some steam or just leave.
EDIT:
Later on the boat in Skellige, when Geralt talks to Yen, there can be a dialogue option:
Geralt: "Work the body?"
Yen: "I guess I've learned something from watching your continuous fistfights."
Geralt: "Heh... Wait a minute, I don't remember ever seeing you around, even once."
Yen (smiles, with a flash in her eyes): "I don't have to be around to know what you're up to, witcher. Best remember that."