We still would like to get feedback for the improved version of the edit conflict interface. So the text in the yellow message box beneath the article headline has been adapted:
"Thank you for using this beta feature. You can help to improve it further, if you leave feedback on this page."
Link: https://www.mediawiki.org/wiki/Help_talk:Two_Column_Edit_Conflict_View
It should look something like this, but with the text above: