I'm not sure to understand but have you tried to click "Make 1:1" in the properties of the sprite ?
You might have to do it in every layouts anyway, but it's just one click, and at worst you probably could include an event sheet with a "on start of layout" event and an action "Sprite set size: Width = Sprite.ImageWidth; Height = Sprite.ImageHeight"
This way, on start of the layout the sprite will automatically be put to the size of the texture it is displaying.