Bug 45855 also shows the problem, which is bigger for some projects than for others: the only true methods to discuss a specific translation are currently edit summaries (for the wiki editors) and code comments (for offline translators).

The "secondary" action menu seems a good place to add such action.
More details at http://commons.wikimedia.org/w/index.php?title=File:Translate-workflow-spec.pdf&page=15

Regarding a way to add translation summary, it was illustrated at: http://commons.wikimedia.org/wiki/File:Translate_Extension_translation_summary_design.pdf

(In reply to comment #2)

The "secondary" action menu seems a good place to add such action.
More details at
http://commons.wikimedia.org/w/index.php?title=File:Translate-workflow-spec.
pdf&page=15

Do you mean the dropdown menu in the "Access to related information" section of the image?

History access is tracked in bug 46791.

Overview of translations in other languages is tracked in bug 46793

(In reply to comment #2)

The "secondary" action menu seems a good place to add such action.

If the discussion is added there, *and* the option to add an edit summary is not provided (bug 46924), then the "add description" button, currently the most visible thing after "save translation", should be reworded/removed/fixed/whatever.
"Discussed" at https://translatewiki.net/wiki/Thread:Translation_UX_feedback/"Add_description"_confuses_users, no idea how to report it.