I have not myself got into a situation where a city requires over 400 goods.
IMO, that’s one of the main problems with this game. Not enough demand for goods to the town to be able to build up a good looking LARGE cargo rail network with transfer yards and holding tracks near the station for waiting trains and whatever else. Personally, I think the game is too centered around the people and passengers. I’d rather be moving more cargo than passengers.
Also, in Locomotion, they were building transfer yards to switch cargo from one train to another but that use a very wide but short station to do it. That worked good and added more to the game. I’d like to be able to do something like that if they would make it so we could but we would need better track configurations. I also think we should have more than one type of goods.
That’ll be on my wish list.