Version 3.0 of my Safari content blocker StopTheFonts is available now in the App Store with a big new feature: iCloud sync! If you enable iCloud sync in the app, then your font blocking settings will sync across all of your devices, iOS and Mac.
There are a few caveats:
Apple's CloudKit framework requires that you enable both iCloud and iCloud Drive, even though your StopTheFonts settings won't appear as a file in your iCloud Drive.
Apple doesn't guarantee that push notifications will be delivered when the app is not running—they might be delivered, or they might not!—so it's recommended that you open the app to make sure your changes get synced.
The first time you sync a device, if its on-device StopTheFonts settings differ from those in iCloud, you'll need to choose whether you want to overwrite its settings or overwrite iCloud. I made this an explicit choice to avoid unexpected data loss. If you're unsure, you can just cancel and decide later.
I hope you enjoy iCloud sync in StopTheFonts. It was a lot of work to implement, more work than I expected when I started, otherwise I might not have started! I did meticulous testing and wrote countless revisions in order to cover every scenario and deliver a reliable experience.