Hi Eino
Sorry, I will not answer your question (because I don't know the answer). Rather I propose a solution I am using on my layout based on these principles:

- a large part of the layout (80%) is based on the aquarium mode modulated by parameters such as train length, type of train (main line, autorails, etc, on power feed (electrified lines or staem / Diesel zones
- few zones for automatically leaving the aquarium mode, to the schedule mode
- schedules being articulaed by conditional tests to decide appropriate schedules (e.g.: uncoupling, if successful, followed by xyz, if unsuccessful reapet schedule xyy
- when the yard operation is finished (loco driven out of the turntable, filled with coal, water and sand, driven to its wagons, the last schedule sends the train to a "take-over block" where normal aquarium mode is resumed.
- whenever a precise action is needed, it is dealt using XML programs (drive the coaling crane, manage the optimal filling of stage blocks, precise position of locos for water loading, etc)
- on the mashalling yard, I made an IR beam to detect coupler location so as to activate the uncoupler at the exact needed moment
- in all places where a train may be uncoupled and a loco leaves its consist or a new one comes to pick them, I use a virtual block and one or two slave blocks
- I use actions to operate combined rail and road operation ("Faller rollende Landstrasse"

Because some resources may lead to a stalemate of locos conflicting to use them (coaling, watering, deashing, I use "outputs" (in the RR meaning) to make reservations for resources and force other locos to wait at an appropriate point until the first loco is finished using a resource. Otherwise you could have many locking points when multiple schedules are driving trails in the steam depot around the turntable.
To avoid any difficult setting of the toggles, at each RR restart, all are reset using system actions triggered by a new start)

The net result is the layout develops an independence of its own (never doing predictable things over and over but rather taking you by surprise

I hope you can follow my simplified and a bit cryptic explanation
An example is with this old video you probably know already where ALL is 100% automatic but where buttons (RR Outputs) start symphonies (schinenbus trips, loco change, marshalling yard operations, etc

Here is the mix rail and road operation with Faller trucks in 100% automatic operation


Feel free to ask questions where you need more detail
Cheers
Jean