There have been at least 50 school shootings in the United States so far this year, as of September 19. Thirteen were on college campuses, and 37 were on K-12 school grounds. The incidents left 24 people dead and at least 66 other victims injured, according to CNN’s analysis of events reported by the Gun Violence Archive, Education Week and Everytown for Gun Safety.
https://www.cnn.com/us/school-shootings-fast-facts-dg/index.html
This is not incorrect data, that is the definition of a school incident. A firearm was found in or near a school. It is not a school shooting, but every school shooting begins with a school incident because it is not possible to shoot in a school without a gun near or in the school.
But this data is not being presented in its entirety as school shooting data, in any instance you’ve cited. Only the data for incidents which involved a shooting in a school is presented as school shooting data.