OpenStreetMap

What "(historical)" in https://www.openstreetmap.org/node/356517631 means? Is it a mistaken import of no longer existing school?

Yes, this was an import from many years ago. The data came from GNIS (http://geonames.usgs.gov/pls/gnispublic) and they include data for some places that don't exist. If you don't see any record of the school on satellite or locally, then please feel free to delete it.

or at least mark it as disused.
I know it's not the remit of OSM, but it's fun for me to navigate through an area in an editor, stumble across points that bear no resemblance to the background reality, thereby at least learning a bit of the history, imagining life in the past, and best of all, taking a break from mapping to research the POI, learn its history and importance (destroyed by fire? flood? oh neat) and perhaps more about the area and its history. But best of all, being distracted from mapping for a few hours.

Is it safe to assume that all that were imported with "(historical)" in name were not existing at time of import?

I tracked down answer - https://geonames.usgs.gov/apex/f?p=gnispq - What does "(historical)" following a feature name mean? "A feature with "(historical)" following the name no longer exists and is no longer visible on the landscape. Examples: a dried up lake, a destroyed building, a hill leveled by mining. The term makes no reference to the age, size, population, use, or any other aspect of the feature. A ghost town, for example, is not a historical feature if it is still visible. Valid features are never removed from the database, but become historical if they no longer exist. The GNIS is unique in containing such features, and additional data concerning historical features based on authenticated documentation are welcome."

I am planning to delete all such nonexisting objects that were added using imports, especially ones mistagged as existing objects.

initial query build to detect subset of objects that should be deleted as known to be nonexisting and despite that imported: http://overpass-turbo.eu/s/FYC

http://overpass-turbo.eu/s/H7K is simpler and still renderable in the browser

I started preparing large-scale removal of misimported objects.

Documentation is starting at https://wiki.openstreetmap.org/wiki/Mechanical_Edits/Mateusz_Konieczny_-_bot_account/remove_objects_that_are_no_existing_according_to_source_of_import_that_added_them

Bot edit proposal will appear at talk-us mailing list and US OSM slack.

Thank you, Mateusz.