Just a point related to the third characteristic of New Editors described in the report which noted "People do more complex, rigorous tasks on their desktop or laptop computers, and short, quick tasks on their mobile phones." (p9).
On the one hand, I wholehearted agree that we should introduce more 'micro-contributions' opportunities on mobile for users (e.g., see this old discussion of Android contribution concepts Reading/Readers contributions via Android).
However, given that "10 [out of 47 study participants] contributed to Wikipedia using their mobile phones or a tablet...(one used the iOS app, and one used the Android app); the majority of these editors were young (under 35 years old)", couldn't this be seen as a trend towards people wanting to edit more on mobile in general and not just small tasks? I found that 10 out of 47 to be arguably quite high (especially the 2 people using apps to edit when they are a relatively low % of overall Wikipedia users and apps have very minimal editing functionality), and it can only increase given the user base will shift more and more towards having mobile as the primary device.
I wonder if it may be a chicken-and-egg situation that users are not performing more complex tasks because mobile editing capabilities are currently quite limited (eg., Visual Editor is presented with reduced functionality on mobile web and not available at all in the apps; it is not possible to create a new page in apps and mobile web on phones).
TL:DR; Are there opportunities to encourage engagement of New Editors through overall improvement of mobile editing capabilities which could be explored in further research and design?