

I have not seen anyone give you a specific answer regarding a better way of handling this situation. I would like to try to do so.
You mentioned that an exhaustive list of terms is not practical, and I agree with that assessment. You also state that you have distilled the rule down to “be civil”. This seems to be an oversimplification requiring further explanation whenever an infraction arises, which seems equally impractical.
A better solution can most likely be found between the two extremes. Clarifying text added to the “be civil” rule might make your stance on what constitutes incivility more apparent.
“Be civil: dismissive, insulting, or overly antagonistic interactions will be subject to action at the discretion of the moderators.”
Well, tell your BFF Jill she’s banned, too.