you made your point, I can understand that,
I am not an expert on this one, but base on my understanding, I think there is a different saying among us on what is a royal tiger del should look like,
Also, base on recent discussion with the local breeder here, which I got all my plats from, the royal tiger del is supposed to have a dominant colors of green and dark.
Although the environment plays role on this, but the green n dark colors are there already, it is their base colors, and it is genetics. It is sometimes hard to see the dark on them because of the lights,..
The word tiger it self came from its pattern which mimic the pattern of a tiger, which is a common sense. However, in case of royal tiger delhezy, the one with green n dark color, is the favorite.
The chance of getting a royal tiger delhezy within one period of birth is very small, that one of the parents must be a royal tiger del.
If I may pick from your images that you posted, then to my understanding it would be the first second pic and the very last pic, those two images show a very dominant green n dark on those dels.
I am not trying to convince you which one is the correct one, you may think otherwise, but I think this is true base on my understanding n my discussion with the breeder.
Other dels may still be called a tiger del because of their pattern, but the royal tiger del is more dominated with the green and dark.