Due to the sorry fact, that vanilla Civ6 is somewhat bland to play (huge gaps in unit lines, missing eras etc.) - started to play some mods, including this one. First and foremost - good job, really. But - "there' no limit for perfection", bhus - I've got some remarks.
1. As already stated - no Enlightenment Era.
2. Russians (for I am one) ... Druzhina cavalry wasn't a light cavalry, it was rather heavy Cavalry, pretty close to contemporary Knights. The meaning of the very word "Druzhina" (rus. "Дружина") is pretty close to the meaning of Hetairoi, they were military companions of medieval Russian princes. Thus - IMHO, of course - it should be a replacement for Knights, not Horsemen. In fact, the Druzhina consisted of two parts - junior and senior one. First, junior part ("molod'" or "otroki") fought mostly as mounted archers, and looked like this
or this
Second part, or Senior Druzhina, acted as heavy shock cavalry and looked like this
this
this
or this
The latter is, in fact, the closest to in-game model.
Functionally in the game, this IMHO proper
Druzhina could be
either implemented as two separate units:
Junior Druzhina Horse Archer (in fact - this could be reskinned Saka Horse Archer with better stats) and
Senior Druzhina Cavalry (replacing Knights), or -
could be made as a single unit, a replacement for Knights, in fact -
shooting Knights with range 2 and decent melee strength (a sort of mounted equivalent of Immortals).