Hi all,
last week we've successfully brought the improved font choice to our mobile skin MinervaNeue onto all wikis. 
It helps to provide our users a better reading experience – across languages, in and beyond latin scripts and a more modern typographic feel to many of our text-focussed projects, taking advantage of specifically designed and optimized fonts for every major system.

Technically we're applying an operating system font first stack for running text (every text element besides main page titles, headings of 2nd order, blockquotes, code snippets, basically most of every page) on mobile devices for most popular systems[0].

Thanks to everybody who has helped in the process of this project, Nirzar Pangarkar for bringing the idea to the table[1],  Jon Robson, Jan Drewniak, and the rest of Reading Web team for co-researching and supporting the implementation, Alex Hollender for fine-tuning design parts as well as documenting pre- and post-change, Brad Jorsch for important reminder of learnings from the Typography Refresh 2014 and Chris Koerner for accompanying the communication externally along the way. 

You can read more on the details on the project page and at the Phabricator task.
Please let us know if you have any questions or further feedback, either by responding to me or on the project's talk page[2].

[0] - https://m.mediawiki.org/wiki/Design/Projects/Improve_mobile_reading_experience
[1] - https://phabricator.wikimedia.org/T175877 
[2] - https://www.mediawiki.org/wiki/Talk:Design/Projects/Improve_mobile_reading_experience

Enjoy and best regards,

Senior UX Engineer, Lead User-Interface Standardization
Wikimedia Foundation

volker.e@wikimedia.org | @Volker_E