Sorry for dumb question, but should I edit rivers and streams? I noticed all rivers in OSM are the same as Geofabric Water is, so I wonder if they update their shapes from user edits, or they make their own? In some places their stuff is inaccurate.
Geofabrik’s files use the data from the OSM database. Any edits in OSM should show up in the Geofabrik files within a day or two. Feel free to edit anything you feel you can improve.