I signed up with Phabricator using my LDAP account. Now, I tried to connect my MediaWiki account to it (as advised here). However, that didn’t work since my MediaWiki account is not part of a global account. And I currently can’t get a global account either, as I don’t own the account on the name’s “home wiki”.
Others will surely have the same problem at some point too.
@Qgil suggested on chat, that with the SUL finalization, there maybe should be some collateral process to fix both the Phabricator login and the Wikimedia SUL at once.