The idea of having Phabricator projects for Wikimedia sister projects has been suggested several times for several reasons, and it starts to be the time to discuss it properly.
From a Project-Admins point of view the answer is simple: if Wikimedia sister projects want to have Phabricator projects, they can have them. It's just that there is hundreds of them, and they have a potential of opening cans and boxes with unexpected content inside. :) For instance, are we ready to receive hundreds of tasks in dozens of languages and a request to localize Phabricator? Or to have users starting VillagePump-like discussions when the admins of those projects are not even following here? We need some coordination before approving the first project.
As usual, a good first step is to define needs and specific usecases.
- Better organization for some specific projects. mediawiki.org, Meta, Commons, wikimediafoundation.org have very specific needs and well organized communities used to work in English first. We might just want to open the door to them right away.
- A bridge between non-technical users and developers. Not many users will know that a problem is related with the Proofread extension, but most of them will be able to tell that their problem is happening in All-and-every-Wikisource. The All-and-every-Wikisource project can be watched by tech ambassadors and other users knowing well that community and its technical links, people that are in a good position to help those users and triage those tasks.
- Localization step 1. As of today, Bugzilla and etc are English-only tools, but only the simple fact of having editable descriptions provides an opportunity to be more flexible. What if a user would be able to file a task in French for #fr.wikisource.org (and/or #French All-and-every-Wikisource, another detail to be defined)? Then the contributors watching these projects could help triaging the task in French for that user, and translate to English if there is a valid new bug.
Feel free to add more.
PS: marking this task as Low priority only to reflect that the ongoing migrations have a higher priority. The own editors of sister projects will probably understand better this discussions and what they want to do with Phabricator once they see Bugzilla and a critical mass of Trello / Mingle projects migrated here.