When you execute a certain testcase, the path to the generated .har is shown in the log.
For Linux looks like are generated into the /tmp folder, I suppose later are copied from there into the actual Reports only if the test execution was in a suite.
You can see the path to it either in Log Viewer:
and furter open it with your preffered tool:
Or from the Console tab you get a direct link to it and it will open straight in Katalon:
