Link, please?
Also, it would be nice if Apple provided at least a small point update to 10.13.4 in the interim, to at least provide support for Messages in iCloud, because all the other OSes has that support now. Really silly and sloppy, IMHO.
Current macOS .4 release works fine with iOS enabled messages in the cloud. There is literally no difference in the user experience. Messages appear across all devices exactly the same. When iMessage in the Cloud is enabled whenever .5 is released. It wil free up some space on your Mac. That’s it. It will still to all intents and purposes be the the same experience. You get a text. It appears on all devices.