I think, it would make sense to have a label wich clarifys high and low processed food next to the nutri score or even better combine the processing level and the nutriscore (like it‘s now) and make a health score out of it.
Discussion
How would you define the level of "processed food"?
Some processing is good and necessary. Some processing not so good. The quantification is even more difficult.
In general, I wouldn't rely on any of such scores.
My approach is:
1) I look at the ingredient list, which already tells a lot.
2) I assess the food quality with my own senses, if possible. Although sometimes color can be misleading.
3) The more bullshit bingo is printed on the packaging, the less likely I buy it.
It takes a bit of experience but over time you get the drill.