According to the latest meeting's notes (2014-10-17) the name will have to be changed to get accepted as a formal group. What about just doing "Third Party MediaWiki Co-operation". That's basically how this started out and addresses the valid concerns of the AffCom.
Topic on Talk:MediaWiki Stakeholders' Group
OK with me. Better: "Third party cooperation". Some people do not like the term "3rd party". We could also use the term "Stakeholder". So this would be "Stakeholder cooperation".
Yeah, "Stakeholder cooperation" is a more neutral wording which does also not exclude anyone (any party). Thus +1 from me.
The name can be: "MediaWiki Fans", "MediaWiki Devotees". I am a devotee! ;)
Non-WMF MediaWiki Users Group
In 2014-11-07 user group meeting, the decision is: MediaWiki Stakeholders.
This will be in the notes which will be published on MW.org by the end of the week.