Risk of altering folder structure in Apple Photos? I've used Apple iPhoto and now Photos for many years, and now have a library of about 32,000 photos and videos. Right now that library is on an attached drive with no rights, so family members can log in and see it.

Looking through the bundle and 'Masters' folders, I see a lot of irregularities in folder names over the years, perhaps between versions, and where I imported other libraries they seemed to get placed in subfolders of the import day, rather than in a higher level date folder. There are also some other quirky things about date and folder location according to ExifTool which I'll look to fix later.

I want to put all of these in a standard /year/month/day folder format as I may move to another app in the near future, but also to make them easier to track in my backups. 

I made some small changes and then rebuilt the database and all seemed well, but I want to ask if there is a known danger of loss of photos somehow due to the way Photos manages this. I didn't find much on the Apple site to explain how Photos does folder level organization (EXIF CreateDate?), since this is what Photos abstracts as part of its UI.
Everything is named per the database and systems, so please resist the urge to move anything. 

You can secure that data with an encrypted disk image if needed or encrypt the whole drive transparently with the current FileVault scheme if that’s what’s the main concern. 

Unless you want to export out the files to disk, I wouldn’t touch it. 

The best tool for making sense / merging / duplicating photos is https://fatcatsoftware.com/powerphotos/ in my experience.