I see that there is supposed to be a limit to the number of extensions... I believe those are things like the farmers and workers quarters. However, all of my cities are well over that limit. Not sure if that is working as intended?

Some features of the game (Stability, deep water sailing, etc.) are not fully implemented in the Stadia OpenDev.

I would recommend commenting about them to ensure they are made known (if they are difficult to find). 

For an alpha version to garner community feedback about game-play specifics, the amount of polish already within the game is surprising. 

Oh I agree. heck, I'd pay money for the game in its current state if I could play through the rest of the ages, I'm just trying to use the bug reporting for what it's intended for. Reporting bugs in an alpha is not the same as b&*^ing about bugs in a finished product :)

This is works as intended for now. They tied extensions to population in an earlier build but removed that limit. They haven't settled in on how they want stability, population, and extensions to work for sure.