As I mentioned previously, MN can get the bibliographic information from the PDF file. PDF already has provisions for this, using standard metadata and outlines. Consider the example that @happycatmachine gives: a journal article that starts on, for example, page 976. The PDF file can start on page 976, and it can include the author’s name.
The PDF specification is available on the Internet. Feel free to read it.
In principle, there should be no problem for MarginNote to use this information in citations. In fact, MN already reads the author metadata from the PDF and it is already stored in MN’s own database. What about books/articles with multiple authors, you say? Just use the first word of the author field. The APA, Chicago, Harvard, MLA, and Turabian formats all specify last name first. That should be enough — better than nothing, which is what we’ve got now.
What about PDFs that you re-author yourself, you say? That’s on you, of course, not MarginNote.
If you want to change the metadata in the PDF file (e.g., if you cut PDF files apart and want to renumber them), you can use Adobe Acrobat or other PDF apps. My assumption here has been that MN would only use the data that is already present in the PDF file. I am not proposing that MN would add a new interface to allow us to edit PDF metadata. That would be nice, of course, but I’m assuming that it simply won’t happen. We users of MN have already asked repeatedly for the ability to edit the PDF table of contents and the MN team has said they have no intention of providing support for that.
So, I don’t think this is a big request — we’re not asking for a new UI addition — and I don’t see that it would be very complicated for MN to do it right. Again, PDF already has provisions for this and MN already reads it.
I agree with @betty77 that while Zotero is a nice app (I have also used it), it doesn’t solve the problem here.
As I see it, the issue is not technical — that can be solved — it is a matter of priority and what audience the MN developers want to reach. If they want to sell MN to academic researchers and students who are writing and publishing, not just using flashcards to prepare for exams, then I submit that getting these features right is very important.
As we have seen from other comments on this forum, the lack of a few features like this can be a deal-breaker for academic users. They will look to LiquidText or other apps that “get it right”.