Indeed, balance is important. There are actually certain balance mechanics that I discovered while making Civ concepts that were stable.
One of them is that almost all Civs have, yes or yes, minimum 5 and maximum 6 military units in the feudal age. Usually there are 4 classic ones (scout, spearman, archer, horsemen) included as unique unit variations, and a fifth “Extra”. Economic units do not count nor do special landmark units.
1.-Scout
2- spearman
3- archer
4- Horsemen
5- Extra: (Early Knight, Early Men-at-Arm, Camel Archer, etc)
English: Scout, MaA*, spearman, Longbowman*, Horsemen
Rus: Scout, spearman, archer, Horsemen, Early Knight*
Chinese: Scout, spearman, archer, Horsemen, ################### Mali: W.Scout*, H.Spearman*, Musofadi*, archer, J.Thrower*, Sofa*
DelhiS: Scout, Spearman, archer, Raider, schooler*.
Ottoman: Scout, Spearman, archer, Sipahi, Mehter*.
Not count: Imperial Official, Cows, Prelates, Rus Militia, King.
Technically, one can be Song as Chinese in Castle Age, because dynasties depend on Landmarks built, and in that age you can build Lancers and Guard Palaces, so they have heavy infantry and cavalry, but as you say, not early as one want by " balance issues".
Mali is an exception to the rule of 5, because this is how they represent that the Mali Empire was great and glorious in its beginnings (1200-1350), but then it declined (1350-1400), and for this reason they do not have a single unique unit in Castles. On the other hand, it also favors its Rush civilization nature, they can practically rush you in 6 different ways, including the Scout rush, but then they fall into imperial due to the lack of units with heavy armor, apart from the Sofa.
ABOUT THE RECENT TESTING IN THE FORUM.-
On the other hand, I find it curious that the tests now show that the unit is efficient, but it is not as broken as some youtubers made it seem, mainly because they did not test a real concentrated attack.