Kind of crappy if you do this from an iOS device and then expect the journal to update the contents on a Mac that's also running the app. It won't show up in the Mac app immediately since the main iOS app would have to launch, read the shared folder, and insert the post into the database... then the Mac would see it via the shared iCloud document.
If this app was not local-only, I could just call some REST API to post the new journal entry to the cloud...