I took a quick look into your project.
A few "critics".
First, why using groups instead of function ? I guess the tutorials and first files you found out were quite old and still using this system.
Replacing "one-time" actions like selecting the selection phase in which the player is (selecting the correct character, then selecting its action, etc...) could work with function.
In your current capx, the group "PhaseTwo" is activated on start as well, which kind of does bug it up a bit.
Yet this is not the complete solution.
It is hard to dive deeply into a 61 events capx with only a few minutes to spare I'm afraid.
To give you ideas, I had made a tutorial on how to make a multiplayer turn-based board game. The idea is to separate each player's actions as much as possible.
Perhaps you could find some inspiration in there as well.