This document describes, what iCloud is storing, when you sync the Photos Library on a Mac with iCloud Photo Library on a Mac with High Sierra. It will depend on your system version, if the people will sync:
See: Use Photos and iCloud Photo Library on multiple Mac computers - Apple Support
After you sign in, these items appear in the Photos app on all of your Mac computers:
- All original photos and videos
- All folders and albums
- Smart Albums
- Names and faces in the People album
- Key photo selections
These items are available only on the Mac where you created them:
- Books, cards, and calendars
- Keyword shortcuts
- Unused keywords
- Last imported album (this album contains photos you most recently imported on a specific Mac)
Your photos or videos must be stored inside the Photos library to be accessible through iCloud Photo Library.
Note the last paragraph - your projects are only visible on the computer where you created them, because they will not sync with iCloud Photo Library. If you delete a photos library, you cannot restore the projects from iCloud, only the content mentioned in the first paragraph. To get the projects back, you would have to restore the Photos Library from the most recent backup of your backups, that still contains the projects.