When we create a wiki page with content from other places (whose license is compatible with our wikiproject), we need to cite the authors of the work. Commonly this is made through the edit summary (because it will be kept in the history of the page). Nonetheless, the current system for generation of PDFs only add the authors which have edited the page in the wiki.
We do need to give credit the real authors the same way we give credit to the wiki users.
That said, it is necessary to have some way of indicate in the collection page additional authors, so that they can be added to the list together with te wiki editors.
T64121: Collection: credits of images should list only the uploaders
T4994: Automatically generated count and list of contributors to an article (authorship tracking)