I couldn't find any. Not any worth citing, anyway.
There are a lot of articles that tell you how to publish, or to be an editor in chief. There are articles that warn of pitfalls, like how you put off your readers if you don't come out on schedule

I couldn't find any consensus on how to edit for zines. Everyone seems to disagree on line edits/changes vs sending them back to the author.
I suppose the best measure would be to see how Robert's editing meets Aphelion's stated goal: to publish original science-fiction, fantasy, and horror fiction, poetry, and features. To that, I'd add a more implied goal: to help authors get started and develop. Lacking any other direction or yardstick to measure performance, if he's meeting those goals, mission accomplished, stop worrying.
Obviously, he doesn't do poetry or features. Other than that, he takes in SF Fantasy, & Horror. Check that goal off as met.
The second goal, helping authors develop, is more subjective. Robert, do you think you're doing that?
Is your editing style the right one? Maybe. It's right for you. Since no one can agree on a standard, there's no evidence you're doing it wrong. Author's who disagree are free to submit to a different editor at a different zine.
I say the way you edit works fine.