Sorry about that!
No worries, just a personal preference. It also allows us to verify things like the below that I saw.
Don't capitalize your groups. make group names all lower case, in name and inheritance, and can target.
I could have sworn Stick/Megiddo fixed that in XGUI allowing input of upper case group names.
Change all of them to lower case, then see if that fixes some of your issue.
Also, you don't need to specify a group inherit's "user". I'm 95% sure, by default, when no other access is inherited, "user" is inherited.
(my team can correct me on that if I'm wrong)
If the case sensitivity doesn't fix your issue, repost the groups.txt after the case-correction.
There's also a space in front of your can_target "!&owner" for superadmin.
That _might_ cause troubles, but I'm not sure.