I'm confused by this problem statement:
No branding or indication the content came from Wikipedia or sister sites
Are you saying there's currently a lack of attribution?
The example https://www.mediawiki.org/wiki/File:Berlin_-_Wikipedia.pdf includes a "Wikipedia" wordmark, how do you plan to scale that to all localised versions of the wordmark and all sister projects?
Once again I recommend to use the global logo for each project if anything.
Nemo