Abstract Onsets and intensity profiles of six energetic (E > 30 keV) electron events common to STEREO A and B (STA and STB) spacecraft were analyzed by Klassen et al. with the STEREO Solar Electron and Proton Telescopes when the spacecraft were separated by <70° in solar longitude. All six events were characterized by earlier onsets and higher peak intensities for the spacecraft with magnetic footpoints at the solar longitudes of larger source separations. The 2.5 Rs footpoint locations, based on Parker spiral (PS) calculations with spacecraft solar wind (SW) speeds V _sw, are compared with 5 Rs footpoint locations calculated by selected realizations of ADAPT-WSA (Air Force Data Assimilative Photospheric flux Transport—Wang–Sheeley–Arge) solar wind (SW) forecast model runs for each spacecraft. ADAPT-WSA footpoint locations support the Klassen et al. results of azimuthally nonuniform injections from two shock-associated events and confirm locations for the flare source event on 2014 July 17. Substantial footpoint differences of the two methods diminish the disparity of the flare event of 2014 May 2 but exacerbate the case of two flare electron events on 2014 August 1. As limited test cases for a comparison of ADAPT-WSA and PS methods at slightly different source surfaces, the Carrington longitude differences range from several to ∼30°. We review the importance and limitations of methods for determining the solar magnetic footpoints for solar energetic particle studies.