That's weird. It's suppose to work if you done all the steps right. Try to check for tips from the comments of the reddit link, maybe some help can be taken from there. As for editing values of weapons or armor - it seems to work fine for both "copy as new" & "copy overwrite" single commands. Haven't had success with the "deep copy overwrite" command though as it fails to save the plugin when exiting fo4edit.
On a similar note, glad to see that some vanilla mashups are now appearing thanks to this early edits. The Daisy Nukes armor from nexus is a good example.