Feature summary (what you would like to be able to do and where):

If a user confirms a translation (unfuzzies it without any changes), and they provide an edit summary, use that instead of the generic Marked translation unit as no longer outdated with no changes (introduced in T49177).

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):

Someone confirms a fuzzy translation and elaborates on why the existing translation is still correct. For example, in this edit summary, I explained why the translation is still correct (or, rather, just become correct). In the translation unit edit summary, this doesn’t appear.

Benefits (why should this be implemented?):

More useful edit histories.