So also it doesn't matter if city number 10 has level 30 or level 40. And it doesn't matter if your city has level 25 or level 39, it just will have to clear the same amount of goods as number 10 city?
Yes the amount of goods should be the same. Level of the city defines your starting time during Endgame. So the closer your city's level to city number 10, the faster you'll start after them.