No one ever picks the Kremlin, which makes it rather boring to play with/against the Rus. To make it more enticing, here are some other ideas for the Kremlin to make it tempting. In my mind, I think there’s room to lean into Rus even more as the “scout building” civ. I’m not saying all 4 of these, just maybe one or another option.
Free professional scouts (not that original).
Unique scout techs such as auto retreat? OR: lower cost? OR: line of sight that decays over time (so as I move away my LOS lingers behind me for a little bit of time before fading away)?. OR: Ability to pick up boar carcasses? OR: ability to see through stealth (for new malians counter).
The ability to convert scouts into horsemen (Free) or Knights (100 gold) when scouts are within range of the Kremlin.
OR the ability to convert a scout into a knight for free if the scout is carrying a deer carcass.
Personally I really like #4 – if you keep professional scouts as a researchable upgrade. Would be another round of the mini-game around hunt and protecting it. #3 may be more balanced because it requires gold still so it would be harder to abuse.