Thanks for the suggestions.
This unfortunately did not work.
My goal is for the TV to power off when Kodi screensaver is activated and power on when Kodi screensaver is deactivated.
OK had not picked up on that requirement when I responded, focusing in on correct interaction between devices regardless of screensaver "suspended" state or not of Kodi libreELEC device. (CEC being a fickle beast to get perfect between combinations of older/newer HDMI connected devices)
But maybe its an alternative compromise for your current layout/setup that may allow soundbar and tv to correctly maintain control and interact with LibreELEC when TV is being switched on/off, where I had also assumed you may wish to use TV CEC remote for interactive control of all three devices. (Rpi4 LibreELEC always powered up and running in background)
When LibreELEC is in screensaver mode are you highly concerned about need for TV to switch off as usually these are shorter periods when we are distracted away from watching TV, intending to return; rather than forgotten, to switch TV and soundbar OFF via TV remote.
(Well in my typical usage case)
My thoughts, are due to fact that most of the time I personally use TV remote as main daily remote for control and operation of TV, AVR and LibreELEC. (When switched to rpi4 LibreELEC as my active HDMI playback device)