Hi Torint,
the transitions are run when a specific boolean is set to true. For all animations except for movement these booleans are set by custom events within the various unit’s event graphs (Unit_Player_Melee etc.). Transitions back are done when that boolean is false. This is done by animation notifies at the end of the animations that fire a custom event in the event graph of the animation blueprint that sets the boolean to false. For movement the animation is set in the top part of the animation blueprint’s event graph, where it modifies a blend space based on the speed value of the owner unit’s current speed float.
I hope that’s enough info to help you out!