Civ V and Civ VI aren't playable due to 1UPT, and as far as I know no mod has restored multiple units per tile. So there's that.
I don't think this mod is a "balance patch" so much as a reworking of Civ IV for marathon games, so I don't know if Vox Populi is something along that vein.
The AI is still a strategic dunce with their armies. It might be possible to build an AI that can use stack strategies more effectively - RI does try and does a pretty decent job. The AI still isn't the best at managing their cities or picking effective techs, so outside of the really high difficulties, a human player can vault ahead by leaps and bounds in late medieval period. Still, I have had AIs throw so many stacks of doom at me that they were able to hold out to the industrial period with something close to tech parity, though my research per turn had to be 5x the lead AI's or something ridiculous. There are few, if any wonders that will singlehandedly swing the game in RI. Starts can be VERY swingy based on what resources you have available - and this applies to the AI as well. Some games they are rushing me with a few light swords at 2000 BC, others they are struggling to put more than two archers in a garrison while I send 6-8 light swords + some battering rams.