Tier 1: Personally, I don't like two things:
a: Strength of 125 seems excessive to me; 100 and 150 would be sufficient, with corresponding stat increases. This is just my opinion, of course.
b: The Fey are undervalued. In my opinion, these mythical creatures should be stronger than the elite Imps, Goblins, and Skeletons. In terms of strength and stat increases, they should be equal to the human advanced recruits, i.e., at the 150 level. Then, we can lower the Goblins to 100, equal to the Imps and Skeletons.
Tier 2: I am definitely in favor of separating the strength of Spearmen and Guards. Also, there is a nuance here: their Tier 1 counterpart, the Assassins, costs more (which doesn't seem logical to me). Therefore, I suggest swapping the Spearmen and Assassins. Archers, although they shoot better than Spearmen, are weaker in melee combat and have lower survivability, meaning they are roughly equal.
Tier 3: Shamans are overpowered.
Regarding Shamans, I'll add this. They can be compared to Furies. They are also female creatures with knives, and the elite version has enchanted weapons. I don't see any superiority of Shamans in combat. Therefore, they are equal (both cost 400).
On the other hand, an Orc can also be compared to an Armored Warrior. The Orc is physically 1.5-2 times stronger and is also a professional warrior, like the Armored Warrior, but its equipment is significantly worse. Therefore, the Orc is not weaker than the Armored Warrior overall, but not stronger either.
P.S. I will write about Tiers 4-7 later.