I know there is a plug-in in LR for iPhoto and Aperture but I have already migrated to OS X Photos (from iPhoto).
Is there a plug-in or some other way to get the photos in and preserve the event and album structures? I'd hate to just use the "Export Originals" from OS X Photos approach where I lose all that information.
I am sorry but at the moment there is no plugin to import from OS-X Photos. The only way to import photos from OS-X Photos is to export them as you already mentioned.
Daniel (from Switzerland)
When I moved from aperture to Fotos, the Fotos importer created an copy of my Aperture Library. Please check in your Images folder if your original Aperture Library still exists. Good luck