Simply due to time & most people using the engine are too busy working on their own games & Simon is too busy coding the engine & doing other things to work on tutorial videos. Sebastian has been doing a good job making a bunch of tutorials for 5.x but unfortunately he decided to do them in German.
As for what you are wanting to do, it would probably be easier to create walking animations for your character where they are already holding the box. You can create different outfits for your character (different clothing is optional) which allow to switch between different states of a character. An outfit could be your protagonist wearing different clothes, or it could be one where the character is running instead of walking or it could be one where the character is portrayed in a different mood (angry, sad, etc).
To show/hide scene objects, you could create a condition in the conditions tab to the right of the scene preview area & then assign the condition to the properties tab of the scene object. Depending on whether the condition is true or false the scene object will be visible/active or hidden/inactive.
*edit: I see esmeralda had the same idea.