It is true that some sites and some organizations attribute a difficulty value to the via ferratas for the entire via ferrata, but in a map we have the great advantage of specifying the difficulties in each section, in a similar way to the sac_scale. In any case the commonly used method accepted is to attribute the via_ferrata_scale to the "way".
In this specific case it is even more useful and important given that the via ferrata is made up of various branches, as you can see in the image: https://ibb.co/KyV4b3s

Regarding the link to the wiki, in my opinion it is not necessary, but if you want, you can do it yourself.