Forgive me as I only have time to quickly skim the thread ...
As far as command delays for a force, I think the numbers shown in the tabs for force delays are only accurate once the entire force has been formed and orders have propagated one time. Meaning that initially you will not have accurate estimates. However, over the course of days and you have already formed your various forces/commands, then you will have this information available for planning.
As you get familiar with the game, you will develop a gut sense as to how long things take. Perhaps, in real life detailed time tables and schedules are for railroads and not combat.
In regards to synchronizing independent actions, in my experience you can try, but it is not possible. Perhaps, one should settle for a more limited timing which determines where you will hit first and then second.
For example, perhaps you want to hit the enemy unexpected in the rear or flank after having shown a weak frontal probe for a half day to mislead them. Hitting them in force in the rear may cause them to abandon their improved positions in anticipation of a frontal attack (due to the probing) to counter the rear attack. Once they have displaced and sacrificed their preparations, then you hit them frontally.
If you delegate a complex attack (multiple levels of command) to the AI, it may select multiple axis of attack and it will coordinate/synchronize its efforts.
Never more! (I've had enough. Sliterine has raised mediocrity to an art form!)