In v12.3 and v21.0 there is no longer a warning message when saving a JSCH that contains a non-existing object.
In v12.2 such a message still existed:
Release : 12.3.x / 21.x
Component : Automic Web Interface (AWI)
Update to a fix version listed below or a newer version if available.
Component(s): Automation Engine and Automic.Web.Interface (AWI)
Automation.Engine 21.0.6 - Available
Solution details: A problem has been fixed where no warning was shown when saving a JSCH object that contained a task and where that task's source object did not exist any more. With this fix, you can save the JSCH object but a warning is displayed informing you of this situation.