UNIT - Creature Balance + Visual Changes

Okay, I'm proceeding based on the identified key issues:

Rakshasa: upgrade < alt, increase initiative from 8 to 10, and possibly swap speed (7 for upgrade, 6 for alt)
There's no need to increase their initiative and speed – they already have a decent amount. Instead, I'd like to see them slightly weakened – they are a very strong unit.
Lizards: upgrade > alt, increase alt's hit chance from 25% to 100%.
I agree.
Crossbowmen: upgrade < alt, reduce alt's damage from 2-8 to 2-6, increase upgrade's range from 3 to 4.
Either don't change them at all, or increase the range from 3 to 4 (only this).
Demons: upgrade < alt, increase upgrade's hit points from 13 to 16, increase the explosion damage by 2-3 times (or more).
It's better not to touch them – it will create a clear imbalance.
Succubi: upgrade < alt, reduce alt's initiative from 9 to 7.
I completely agree.
Skeletons: upgrade < alt, increase upgrade's damage from 1-2 to 1-3.
There's no need to increase the damage (it will create an imbalance due to the quantity); it's better to increase their HP by 10%.
Vampires: upgrade < alt, change alt's stun factor from 1 instead of 3 (approximately 30% chance instead of 70%), increase upgrade's hit points from 35 to 45.
It's better not to touch them – it will create a clear imbalance.
Dancers: upgrade < alt, reduce alt's damage from 4-6 to 2-5.
I agree + reduce the upgrade's damage by 1.
Lukari: upgrade < alt, remove direct hit or enhanced arrow from alt, and possibly swap initiative (11 for upgrade, 10 for alt).
I agree.
Shields: upgrade > alt, increase alt's damage from 1-2 to 2-2.
There's no point in changing them.
Bone Crushers: upgrade < alt, increase upgrade's damage from 3-8 to 6-8.
There's no point; it's better to add HP.
Warriors: upgrade < alt, increase upgrade's hit points from 12 to 15.
I agree.
Shamans: upgrade < alt, give upgrade 16 mana.
Either this option, or don't touch them at all.
Off the top of my head, without calculators. It's not a fact that these are the best changes. But it's almost certain that these are appropriate changes (in the right places and in the right direction).

What's good here: a minimal number of changes (1-2 per pair, a small number of pairs), there are no too drastic changes in stats (all within 20-30%), there are no insignificant bonuses that don't change much (like +2 defense), there's no creativity/arbitrariness in adding new abilities, and an ability is only removed once (where it's clearly excessive), and in most cases, the overall logic of the units is preserved (characteristic strengths are not averaged), and the key characteristic of unit perception – speed – is not changed (with the exception of the swap for Rakshasa). It's not a fact that these are the best criteria for selecting changes, but the very fact of their existence reduces arbitrariness (subjective desires) and adds to the systematic approach.

Next, a little creativity regarding the frankly failing tiers:

Wyverns (expensive, weak, and without blood): increase growth from 2 to 3, or make them available on week 1 (lower the threshold).
There's no point; it's better to add 5-10% HP.
Necrodrakes (very expensive and weak): significantly (by 2 times?) reduce the overall cost of building dwellings, both in general and for mercury.
Oh, that's a very good idea. I agree.
You can also recall units that are subjectively weaker and have weak abilities. For example, the weak flame of gnome dragons (increase it by 2 times). These things, although not as obvious as the imbalances above, have a pleasant side effect – bad abilities become better. At least, they can be considered in a vote. Plus, you can raise other subjective questions, for example, in the pair of Nightmares, is there an imbalance between upgrade and alt? And if there are a large number of votes confirming the imbalance, only then come up with a way to balance it (for example, reduce the alt's aura damage).

Furthermore, you can look at the races. We see that the Elves' 2nd and 3rd tiers have been weakened; you can increase the growth of fairies by 20% (as an option). Or, since the 4th tier of Demons has been weakened, you can make it available 3 days earlier (lower the threshold). These are not independent changes (there's no point in simply strengthening fairies), but rather consequences of the previous ones.