xfconf does not set appearance properties on XScreens correctly
Multi XScreen configuration xfconf ignores theming on all XScreens other than 0.0.
Launching xfce4-settings-manager on the desired XScreen and settings appearance only changes on DISPLAY=:0.0.
Command line is also ineffective in that is works but only affects DISPLAY=:0.0. DISPLAY=:0.1 xfconf-query -c xsettings -p /Net/ThemeName -s "Adwaita-dark" = changes the theme on 0.0 not 0.1. DISPLAY=:0.2 xfconf-query -c xsettings -p /Net/ThemeName -s "Adwaita-dark" = changes the theme on 0.0 not 0.2.