Hi Dobromir,
You’re right about the fact that the Node.js process, which is the Appium Server process by the way, is still running when your test failed. This is intended because if we close that process automatically when test scripts is failed, the test apps will be closed too and users will not be able to debug on those apps.
As for case when that process is still running when you stop the Mobile Object Spy, we’re aware of it and will have a fix for it soon in the future.
In the mean time, please spend some efforts to close those processes using Task Manager (on Windows) or Activity Monitor (on macOS)
Thanks a lot for using Katalon and giving us your feedback.