the generation of passengers should depend on the size of the destination city.
I have a city here that has not yet been built (0 citzen) and the train station for this city is full of visitors.

I know you are aware of this point, and i know you can't program all aspects at the same time. so this is no jostling only a todo reminder ;-)

BTW
I build the 6th (and last posible) city after 44 hours.
not all are growing because the lack of apples.
i had no hurry, i only built the most necessary buildings for the supply. the research was done through the universities and i only researched the most necessary things. I did not build transport lines I used "teleportation". if you play everything like in vanilla, you might need a little longer. i had a lot of idle time with the 10x speed, so the estimate of the effort is very inaccurate.
I have too much currency left. (but I haven't researched everything either)

Thanks! That's a good balancing factor to include :)

And thank you a lot for your extensive testing, that helps a lot!