It should be possible to add images to article templates in the same way as adding them to FAQ Articles or when composing an E-Mail, i.e. by copy/paste or uploading them in the editor.
Currently, adding images in a template is only possible by including the image encoded in base64. If you have many images, you will exceed the character limit quickly.
We would like to create some image-heavy step-by step procedure templates but that is not possible at the moment.