What if we tried to create a movie script together!

Sorry for the delay—workload and internet problems...

the forest dwellers preferred to rely on the same-wise Druids, seasoned in battles with enemies of the forest.

The comma after "forest" should be... and, seasoned in battles with enemies of the forest, Druids.

These are just and devoted servants of Silanna – the goddess mother earth.

"Goddess" is needed here, AND maybe capitalized? Goddess Mother Earth—is that better, more correct?

But recently a battle with the undead took place in the grove. The battle was short, but extremely cruel and bloody. And while the council of druids led by Hilael discussed what happened with other guardians, among the students of the school of combat dance there was also a leisurely conversation about the event. Everyone was stunned by what had occurred and put forward their own versions of the incident. But one elf stood out among the other students. Throughout the entire conversation he remained silent and simply calmly listened to the various versions of those speaking. The name of this elf was Silbern.

Is this referring to the meeting described by Zeratul? It seemed to me that elders should seclude themselves from everyone... like Kalgi used to do. So Hilael should also be alone—so that no one overhears... you never know... Rewrite the sentence, removing any mention of a council.
And about the school—what exactly were the young students discussing among themselves? The recent attack by zombies and other creatures, or Agremay's betrayal and the loss of part of the artifact? Obviously, they shouldn't have known about the artifact at all. Therefore, they could only discuss the attack and be stunned by this event...
What happens next?.. There is a list of those killed... What can adult elves do after a battle? "Lick" (heal) wounds, interrogate captives (if any), report losses and victories of the battle to higher command (the commander-in-chief)... What can the youth do? Get in the way, brag about trophies (a cleaver snatched from a zombie's corpse or something similar), they might help with the wounded and so on...
In other words, just try to visualize the situation and think about who does what after a battle. Are you a student? Imagine that a crowd of over a hundred people gathered in your city square, brawled, and fought. An ambulance arrived—tending to the injured; the police arrived—breaking up the fighters and investigating; onlookers, old women gathered... youth (students, high schoolers) are running back and forth, talking... Now imagine that this scuffle was much larger—a homemade bomb was thrown, someone had a knife or brass knuckles... No longer just wounded—there are victims.
If elves love their kin (relatives, friends), they should feel depressed, grieving... Maybe one of the parents of these students of yours was killed in battle... But from your text, none of this is clear—the youths are leisurely discussing the event. Even an event where two students fought would be discussed with emotion... and here we have a whole battle with enemies and victims... I just don't see this depression among the elves; I don't see actions to restore order, help for the wounded, burial of the dead...

An option with additions: You can write it in instead of your paragraph... or construct something of your own

But recently a battle with the undead took place in the grove. The battle was short, but extremely cruel and bloody. What happened affected everyone and knocked the peaceful life of the forest elves out of its usual rut. And while the high archmage (or whatever they are called among elves) Hilael secluded himself in his Consultative Chamber, conversations and discussions about the event did not subside among the other elves. Elves—from the very young to experienced men and women—helped the wounded, buried the dead, restored the mutilated nature of their forests and, of course, discussed what happened, putting forward different versions of the attack...
The young elf Silbern, a graduate (or not yet a graduate? then practically a graduate) and pride of the school of combat dance, also took part in eliminating the aftermath of the battle. Attentive and taciturn, he silently listened to the conversations of others and... (what was he doing there? Helping the wounded? Burying the dead? Restoring nature? Collecting the weapons of defeated enemies and handing them over to elven smiths for smelting... finish it yourself, but an elf simply could not stand aside...)

From his first year of training he was distinguished by persistence and tenacity in studying the complex and graceful technique of combat dance.

"Technique" is needed here

He was of average height, somewhere from 170cm to 185cm.

Is this the average height for elves? For humans, as far as I know (imho), average height is from 150 to 170... If higher (like your elf)—that's a tall person... Will elves be taller than humans in our book? And what is the average height of dwarves? 120-140? 150-160? We need to decide on this, so it doesn't turn out later that some one-and-a-half-meter dwarf "looks down upon a six-foot elf..." By the way—180 cm is 6 feet.

I replaced frequent repetitions of "he" in some places, added missing commas, coordinated some sentences, plus the height thing.... It turned out like this:

Silbern was an extraordinary student. From his first year of training he was distinguished by persistence and tenacity in studying the complex and graceful technique of combat dance. Standing approximately 6 feet tall, slender and strong, some might have considered him a handsome youth. His long white hair, according to the custom of combat dancers, was braided into a plait. Bangs fell over his young and daring face, longing for adventure. A string with a silver leaf was tied to a lock of hair above the left eye. A small emerald, like a dewdrop on a flower, adorned this leaf. This was the only thing that reminded Silbern of his parents who died prematurely when pirates-orcs attacked their ship. The young elf himself was at home under the care of his grandfather back then. His grandfather had once been a glorious archer and therefore taught his grandson to be proficient with flexible elven bows. But Silbern preferred mastery of the beautiful elven sword dance over simply being skilled with a bow.

Now, Silbern was as shocked by what happened as the others.

"What happened" (случившимся) here

They are sure that the elven race will exist as long as at least 1 unicorn lives, and therefore Killing a unicorn elves consider the most terrible crime against their people and their goddess Silanna.

"Killing" with a lowercase letter, comma before "that"...

In addition, 2 druids and 1 elder of the druids died, which made the entire forest folk think seriously. The losses of the undead were almost three times greater, but they are dead and can be raised from the fallen living; moreover, the very fact of their invasion was baffling. Their goals and intentions were completely incomprehensible.

Here I just don't understand why the fact of their attack is incomprehensible? The fact of a zombie invasion shouldn't be baffling. They are zombies, corpses, risen skeletons... An abomination, a contradiction to everything living and beautiful that the refined and lovely elves cherish so much... What motives could the undead have? Of course, the most vile, disgusting ones... which are sickening even to talk about. Kill all the undead and bury them so deep they never crawl out again...
This is generally from the perspective of the elves, I assume... just my judgments... you can revise the paragraph a bit... but at your discretion...

A young dark elf, a graduate of the School of the Invisible Hand, sat confidently on this lizard.

Uh... I wanted to correct something here, but forgot... maybe I'll remember later... or it doesn't matter.

The rider's height was approximately 10 cm less than Silbern's height.

While the dark elf is sitting, you can't know exactly how much shorter he is... You can only measure when they stand and align... Cut this sentence—it's redundant.

Their build was the same – both looked slender and fit.

Uh... maybe later, when Albin gets off his lizard-horse, we give a brief description of him?
Like—The arriving dark elf turned out to be slightly shorter than Silbern, but just as slender, fit, muscular... and so on regarding the appearance of the dark Albin... write it yourself at your discretion. And I'll correct it if something is wrong :)

The rider held himself confidently, but surprise was clearly written on his face.

"Confidently" and "clearly" don't blend well... Maybe like this:
The rider held himself confidently, although a flicker of surprise crossed his face—he was among forest elves for the first time.

I greet you, Albin-, Hilael said. Silbern understood what the stranger's name was…

Forgive me, but this sentence looks like a "deus ex machina." It is completely unclear how Hilael knows Albin? Why did Albin come to the forest elves? He was traveling to some city... Did the forest elves summon the dark elf? Did they intercept him on the road? All this needs to be clarified... Otherwise, it's a "deus ex machina"... appearing out of nowhere...
In short, more thinking is needed.

PS: Also regarding the names of creatures and undead—you write them sometimes with a capital letter, sometimes lowercase... Creatures was capitalized, Druids once capitalized, then lowercase... unicorns (sacred animals) lowercase... Review the text and decide whether we will write all names with a capital or lowercase letter. I suggest lowercase. Everyone—creatures, druids, unicorns, zombies...

Respectfully, Simas