Currently, after scrolling down in the translation editor, the header where the publish button is becomes sticky in the main document. However the cards in the tools column do not move at all as the user scrolls, which generates a gap on top:
The tools should instead move up as the user scrolls until they are 20px to reach the top edge of the screen. At that point the tools panel becomes sticky. 20px is the separation between cards according to T158410 (although the editing card and the instruction card are not following it currently, which is reported as a separate ticket).