Based on a compromise with some members of the English Wikipedia community, there is a special local override capability which allows English Wikipedia to override the Wikidata description for an item by using a magic word inserted into the article's wikitext. Because this solution was not fully in place at the time of Android's initial development of this feature, the apps currently "blacklist" English Wikipedia and do not handle description editing in an special way. Now that the service exists to tell us when a local or central (Wikidata) description should be used, we can make this flow better. So...
As a mobile description editor, on an English Wikipedia article. When I press the article edit pencil, the first section edit pencil, or the placholder CTA when no description exists then:
If a local description is in place, open the Wikitext editor and place the cursor at the magic word.
If a central (Wikidata) description exists I should see the same editing flow used for other languages description editing
If no description exists I should see the same editing flow used for other languages description editing. This new description should be saved to Wikidata.