I know there’s some changes coming with checklists and due dates (looking forward to them). Something else that would be useful, perhaps as an option as it may not suit everyone:
When a check list item an/or task is marked as complete: strike through the text. Would help when scanning a longer note especially.
And, collapse the paragraph to show just the first line. This would be helpful: served as a reminder the task has been done, can open for detail, but don’t lose screen space or mental attention to something that’s not current.