But nevertheless, something seems not quite to work as expected. While I can change the styling, even if I remove the figure component, the image is still there. 
Yes exactly. It is not working yet. I don’t have the knowledge to find out what is wrong. If you have any ideas, they are very welcome! It would be a big addition to my sites to have this image preview 
That seems to be a bug, I also tried to use another preview name like custom in the image.yml and rename the stuff in the plugin accordingly, but that doesn’t work either.