As you preload a scene, you need to instance it in order to play with it.
You can change your first line to:
onready var Spaniard=preload("res://Scenes/Enemies/Spaniard_Enemy.tscn").instance()
instance() later in the code, for example if you will have multiple copies of it:
var new_spaniard = Spaniard.instance()
You can now access to its childs and properties.
Then, if you want to add to viewport/screen, you need to add it to tree too: