General Notes and Keynote Legends should be Resource assets which can be placed on multiple Sheets.
In the Resource Browser (or the pending Manager), you could have a Notes Folder which has 'Exterior Elevation Keynotes', 'Floor Plan Keynotes', etc.
That way I can have the same set of Keynotes on multiple Exterior Elevation Sheets, for example.
Right now, if you have two sheets of exterior elevations or floor plans, you cannot use Sheet Layer Viewport annotations and automatically have Keynote 12 be the same on both sheets. If you want to have coordinated keynotes across multiple sheets, you have to do all your annotations on a Design Layer. Then you have to make a specific SLVP for the Keynote Legend on each sheet.