Your mod was the right reason, why i should start playing civ VI !
I was modding civ V a bit and i had a lot of almost same ideas (like a ship of the line, galleon, predreadnought, motorized inf, snipers, line inf, marines...) but my mod was not succesful like yours (fullfilled with bugs that makes the game to crash), so i surrenderred.
But i have bunch of ideas, how to improve your mod:
1)Decrease range from "ship of the line" and "galleon" to 2, 3 is IMO too much for midgame. While range 2 for unit "artillery" is IMO bit underpowered. Increase it to 3, like it was in civ V.
2)Siege units are very OP. (Not sure what you have done in v7.3, Im still playing with 7.2, but is "update under way") They have strengh very close to meele units in late game.
set it to: "trebuchet"=31/43 (strengh/bombing strengh), "bombard"=41/53, "howitzer"=50/63, "artillery"=58/72, "mobile arty"=66/81, "rocket arty"=73/90,
"assault gun"=65/76, "self proppelled gun"(next to rocket arty it looks useles)=72/85
3)Move the "UAV" to "automated gun" promotion and upgrade line. Set the gatling gun to 57/57 (like in civ V, ranged str is same like strengh), "machine gun" set to 72/72 and "UAV" set to 80/80.
4)Add "skirmisher" to early industrial era as sniper unit. Maybe somethink like 52/55. (Oops, "Ranger" is already there) Move "sniper" to modern era, maybe "replaceable parts". Because his stats fits the modern era much more than the atomic. (dont forget to change description)
Give the "Information era sniper" ability to paradroop. Just for fun.
5)More paratroopers!
6)Move "battleship" to early Atomic era (WWII) and add "dreadnought" in early modern era (instead of battleship). Models could be found in my old civ V mod. There you can find many models for both battleship and dreadnought (and pre dreadnought too), so you can add them as unique models for other nations.
7)Guided missile, more variation. I hope, they can techically work in the same way as the nukes do. Can be stored on missile destroyer, missile cruiser and attack sub.
8)Small bonus for naval meele vs naval bombard, somethink like +15℅ strengh.
And some bonus, if still is not there, for light cavalry vs siege and ranged. Just for balance purpose.
9)The transition between rennesaince and industrial era is terrible. I am missing somethink there.
https://forums.civfanatics.com/threads/the-enlightenment-era.551446/ THIS !!! I used this in my old civ V mod. Now i am missing it. If you (or some other modder) is going to add it, then we have a lot of new work. :
Move "ship of the line" and "frigate" and "corvette" here. Move "galleon" to rennesance. Add lioght naval ranget unit "Carrack" next to the galleon. It would be as a part of the naval ranged line. Use model from Civ V "Nau" or from current civ VI caravel. (The ship in Civ VI named aravel is actually a carrack) then add new unit model for caravela from civ V.
Move "line infantry" and "skirmisher" (now, ranger is industrial sniper, while skirmisher is englihtment sniper) and "field gun" and "naval infantry" and "howitzer" and "lancer" and "cuiraseer" to englihtment era. Now, we have some missing units in industrial era , but one day we will fill them. Change city defend unit art in medieval to trebuchet and in rennesaince to bombard, in enlightment era to field gun( or rather to howitzer if we would have another industrial era siege unit). This giant changes are because units from early industrial are actually from earlier Napoleonic wars. And the rennesaince era in vannila is quite too long (1500-1850). The englihtment era now would be from 1700 to 1850, while rennesaince would be 1500-1700. Models of skirmishers and many more could be found in my old civ V mod.
Here is my old mod, models are not my work, the core of the mod is also not my work. But i think, you are free to use any models and icons in your mod.
..........here is going to be the URL for the file, tomorow.............
I hope, it is visible to you, if not contact me.