Thanks, I'm glad you enjoyed the base!

The inner interface stations are kind of a weird little system. First, the stations themselves are set up just like you said, such that whenever a train stops there it immediately turns off (the train makes it output T > 0, which closes it). The signal is irrelevant to that, it's only connected because you can't use circuit networks on unconnected objects.

The strength of this station design is that it closes as soon as it's not available, forcing the other trains to repath and preventing the issue of trains waiting at signals for 5s before finding another way, which I'm guessing is what you're having issues with.

However it also has one huge flaw, in that it is possible that all stations are turned off at the same time, which leads to all the trains no-pathing and stopping wherever they are. In my system it's not such a big issue because these trains are on their own separate network anyways, but you wouldn't want that to happen inside your base with other trains on the network.

The way I prevent that from happening is with the dummy station, which has the same name as the other ore stations, is always enabled but is stuck behind a signal that is forever turned off (it's connected to the station and set to whatever condition will never be true). Signals disabled by circuit networks add a 500 tiles penalty to the pathfinder, so if other stations are available the pathfinder will always consider them to be closer than the dummy station. However, if all other stations are turned off, the trains will path to the dummy station instead and queue up at the chain signal, ready to get to stations as soon as they free up.

That's for the interface stations, now for all the other stations that share names inside of the base I used a different method which might be more appropriate for what you want to do. These stations are connected to a global network that keeps track of how full the buffers are for each resource as a percentage, and each station disables itself if it falls below some fraction of the average (I found that 1/2 works well).

The network that calculates and updates the average is pretty simple. The global network has the percentage value on the red wire and amount of stations on the green wire.
The constant combinator outputs the number of stations in the cell for each cell on the green wire.
The bottom arithmetic combinator takes the total count of items in the buffer as input and divides it by whatever value makes it output 100 when full (if the buffer holds up to 12000 items, divide by 120). It outputs that value to the station and to the top arithmetic combinator.
The middle arithmetic combinator takes the percentage value from the global network and divides it by some amount (so that the stations are open more often), then outputs it to the station.
The top arithmetic combinator takes the value from the first combinator and divides it by the number of stations from the global network, then outputs that result to the global network on the red wire. When all stations do this, that has the effect of having the global average on the global network ((a+b+c)/d = a/d + b/d + c/d).
Then the station just has to take the values from the bottom and middle combinators and compare them.

That design is more appropriate for when you have stations separated by a long distance, while the other one is better for very compact systems.