When you are using iCloud Photos on macOS 10.14 Mojave, called iCloud Photo Library on macOS 10.10.3 to macOS 10.13, the titles, descriptions, and keywords will sync with iCloud between your Macs, just like other metadata you change on a Mac. You will not see the titles, descriptions, keywords on an iPhone or iPad, because iOS devices cannot display these data. But they sync to iCloud and are available on other Macs.
This is explained here: Use Photos and iCloud Photo Library on multiple Mac computers - Apple Support
Photos works with iCloud Photo Library so you can access your photos and videos on all of your Mac computers.
iCloud Photo Library lets you access your photos and videos on multiple Mac computers, as well as your iPhone, iPad, iPod touch, and iCloud.com.
Just sign in to iCloud with the same Apple ID on all your devices. You can turn on iCloud Photo Library in Photos > Preferences, or from the iCloud pane in System Preferences.
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
- Keywords
- Memories
- Key photo selections
These items are available only on the Mac where you created them:
- Books, cards, and calendars
- Slideshows
- Keyword shortcuts
- Unused keywords
- Last imported album (this album contains photos you most recently imported on a specific Mac)
- Names and faces in the People album
Your photos or videos must be stored inside the Photos library to be accessible through iCloud Photo Library.
Published Date: Sep 20, 2016
I posted this as a user tip here: Use Photos and iCloud Photos on multiple Mac computers
Apple edited the original support document for iCloud Photos on a Mac (Use Photos on your Mac - Apple Support)n ad removed unfortunately all references to the iCloud syncing between Macs. That is why I had to track down the original version on the magnificent Wayback Machine.
