I posted some ideas in the main suggestions post and a lot of them were unit based but in the middle of posting that long list of suggestions I noticed the topic spefically of units so I copied those and pasted them on a notepad and pasted them here
1. A Gnome faction, or at least a way to get gnome troops (perhaps as caravan guard or something), it's odd they are playable race and you get gnome heroes AND they are gnome NPCs yet gnome aren't (as far as an tell a part any troops) (Side note: I would ask for Halflings but you seem to having Gnomes kind of acting a fusion of the two anyways, but if you wanted to incorporate halflings that would be fine by me.)
2. A Goblin faction, or at the very least goblin raiders, because considering the D&D style, and goblins being one of the common races it's odd they don't exist, also if you include them could them as a playable race that would be cool (I'd recommend +1 Str, +1 Agl, -2 Cha for stats BTW)
3. Sans the protaganist and hero characters their doesn't seem to be any female dwarf troops, perhaps you could possibly get them the same way you get human peasant woman (in villager groups that get kidnapped by bandits).
4. Could you make female Orc Slaves, it's odd that any slave trade would only have men.
5. And on the subject of Female Orcs, it's odd that the only female Orc troop type is an Orc Shaman, could you add a base "Orc Tribeswoman" or something like that, that you could get from Prisioners.
6. And on the subject of Orcs Class trees, it seems like it could be a bit more expansive as it stands it's a bit linear for a faction tree, and lacking a lot of diversity, I know orcs in fiction tend to be somewhat narrow focused, but I think it might be worthwhile to add some long range combat (maybe threw throwing or something like that), some horse archers, and some magic (perhaps in the form of male shamans, which wouldn't be too out of line), and if you are gonna focus on melee combat you could at least have them have a good diversity in combat styles rather than just simply "Mounted Branch" and "Infantry Branch"
7. Also on the subject of Orc Class trees, its odd that the base male orc class is "Orc Looter", especially when you get them from villages, and such, perhaps, make the starting class "Orc Tribesman" and make looter a promotion
8. The mage faction is kind of weird, it's odd that human mages are (or less) attached to one and only one of the human factions, maybe add you could add mages (and clerics) to the other human factions (just one or two classes each is fine honestly)
9. On the subject of the Mage faction, instead of being an (almost) exclusively mage factions, perhaps you could make it a seventh human factions with an emphasis on magic expanded a lot because it's literally entirely linear, also don't make the starting unit a mage it's kind of odd for magic (a field that in most works of fiction requires massive study) to be know completely by the masses of any culture, I made an example troop tree for magic heavy culture notice the intentionally small and limiting physical branch, it serves to few purposes to act as a possible replacement for the guard class, that you have and to show that not literally everyone in the country is a freaking mage because that's really wierd. Also noticed the branches on the mage tree it's to allow diversity, it gives the players three options with the mages one to make them pure mages (this branch should probably have the better spells along with more deverse spell), the mage knight branch (which should have the worst magical abilities of the three mage branches, but more than make up for it in mounted mobility, decent defense, and melee combat abilities), and the sage branch (which should have better mage abilties than the mage knight, but worse than the master mage, makes up for it with faith abilities this also gives the Mage factions healing abilities that the other factions have (assuming you add clerics to other factions)).
Example Troop tree (The cultural name is magalian for this example, and I use the same color coating you do)
-> Magalian Mage Rider -> Magalian Mage Fighter -> Magalian Mage Knight
-> Magalian Novice Mage -> Magalian Mage -> Magalian Adept Mage -> Magalian Expert Mage -> Magalian Master Mage
Magalian Recruit -> Magalian Sage -> Magalian Archsage
-> Magalian Militia -> Magalian Fighter -> Magalian Veteran Fighter
-> Magalian Cavalary -> Magalian Veteran Cavalary
-> Magalian Horse Archer
-> Magalian Skrimisher -> Magalian Archer -> Magalian Veteran Archer
-> Magalian Veteran Skrimisher
8. Also as you can figure from my earlier ideas, an idea I had to make it so people can get females Elves and drow from both rescuing elven/drow civilians, but another idea I had was that for Elves and Drow which you seem to be trying to make them relatively progressive in women's rights was that perhaps you could female troops along with male troops from villages (such as in the More Women mod) for the elves and drow, same with the mage faction.
9. Mercenaries of other races, it's weird that all the mercenaries are still human (And if you have mercenaries of other races perhaps allow female mercenaries for Elves and Drow)
10. (Repeated from the main tread suggestions because it kind of applies to both threads) Mixed-Race Characters and units, namely half-elves and half-orcs (Though other options would be cool), I wouldn't mind to much if they were protagonist and hero characters only but having Half-Elves and Half-Orcs as mercenaries or having a small chance to appear in villages or something would be nice.