It would be nice if we have the feature that lets me make changes to edit summaries after submitting the edits. Could there be an existing script that I can install that lets me do that? If not, MediaWiki shall develop one.
I presume the reason why we can't edit edit summary is simply because we don't have technology yet. It should eventually have the script that enable option to change the edit summary even after saving it. Sometimes I should've add to summary or forgot after hitting save button and really wanted to correct it. I believe changing edit summary will be available in the future. We can suggest that to MediaWiki staff about that.
I'm talking about editing the summary while viewing list of changes on revision history page, user contribution, etc, therefore not requiring to re-saving the article. Gotta simply develop the script for that. I agree right now it's impossible as you said, w/o re-saving the article, but I believe this will be possible in the future once MediaWiki develop the script for that. I imagine once we have that feature, I can only make changes to summary of my edits, not somebody else's.