Trail field vs tag

Some path have IMBA Trail Difficulty as trail field and are rendered great using a theme in a biking app.

Other paths don’t have that trail field and use a tag to indicate

Can we write a script that converts all tags into trial features? This duplication is confusing!

(this forum is better to post this and not Q&A)

Can you give an example of each type of trail? I am not sure what you mean by “trail field” or by converting a tag to a feature, is that terminology used in a particular editor or app?