How can I center an object symmetrical at the center of my editor?
You could open the grid, that way you can add the object on the centre squares.
At least that is a basic way to do it… maybe there is a better way, but I don’t know any XD.
Center in the editor view only or in the game?
For the view, you can click on its instance in the list.
For the game, you can change the camera to center on the object. Or you can use a position action to position it where you want.