Thank you for your kind answer. I am very happy if my comments can be of any help for your projects - already as an encouragement to continue developing great games ! I am ready to help you further if you want. I have added some more discussion about the tax balance issue here.
Here is a screenshot of how I manage taxes in most of my cities :D And I think there is still some margin to go above 50% tax (whatever this means). The worst thing about it is probably that I have absolutely no use of the collected fortune... But since they are extremely happy, it would be rude of me not to accept their generosity.

My first suggestion would be to lower the +5 mood per museum level and +4 per tavern level. It seems far too much compared to the penalty of overcrowding, although I have no details (having 400-500 citizens is not a problem if you have a few levels of these buildings).
Another option would be to think the mood system differently. Here is an interesting way of how it is implemented in another game I know (chronoscz.itch.io/c-evo). You start with a fixed amount of morale points (eg 20). For each point, you can have a free citizen that you would assign to any work. As your city grows, you reach the morale point limit. Technically, this translates into part of your citizens being assigned as city guards/police to give you more morale points. In addition to this, you can also lower the tax or have special buildings that increase the morale/mood limit, just as in your game.
Their system is even more complex than what I described, and I am not sure I wrote it clearly. But the main idea is: mood is not just a 0-100 indicator, it is a parameter that affects how many of your citizens you are allowed to use, part of them being frozen for maintaining security in your city. And you go from small penalty of overcrowding, to fighting for the right to increase your population.
I don't know if any of these suggestions inspire you for the fix. Maybe tax and mood is not the funniest part of the game to work on. It's mostly a technical question, and it can get very complicated. Going for a simple fix could be enough, and free time for other questions. Anyway, feel free to discuss any topics of your game.
