I've updated to LE10.0.2 yesterday and the CEC-Bug is annoying...
I've now installed your testbuild and added vc4.inval_delay=3000 to cmdline.txt (2000 was not enough and turned TV back on sometimes).
I would say it now works good, but not as good as on LE9. If I turn off the TV and AVR at (nearly) the same time, the TV goes back on. If I turn off one device first and some (2-3) seconds later the other device, everything is ok.
I am using a LG TV and Denon AVR.
Thanks for your work!
(BTW: I need CEC only to turn on my TV (with kodi-send --action=CECActivateSource), because it can't be powered on over network.)
Have you tried:
I found that worked better for me overall.