During translation i see notification area/systray/system tray i the source.
Orage uses systray.
Parole and power manager uses system tray
Others use notification area.

So i suggest to use the same for consistency.
https://docs.xfce.org/xfce/xfce4-panel/systray have systray in the url and the page says both tray icons and notification area.
Seems notification area is the most used.

It might be a little confusing calling it notifcation area if it have nothing to do with notifcations (the messages on the desktop).

I spam this bugreport to both Orage, Xfce4-power-manager and Parole.

There is also "tray icon" in Orage and Parole could be changed to "notification icon".