For the records, when it comes to component maintenance responsibilities of WMF teams, I am aware of the following documentation apart from Developers/Maintainers:
- Reading/Component responsibility
- Wikimedia Language engineering/Code review statement of intent
- https://phabricator.wikimedia.org/project/view/20/ (RelEng)
- https://phabricator.wikimedia.org/project/profile/1212/ (Perf)
- https://phabricator.wikimedia.org/project/view/1025/ (Ops)
- https://phabricator.wikimedia.org/project/profile/48/ (Multimedia)
- https://phabricator.wikimedia.org/project/profile/45/ (Research)
- https://phabricator.wikimedia.org/project/profile/1174/ (Discovery)
- https://phabricator.wikimedia.org/project/profile/65/ (Collaboration)
Maybe helpful, for reference.