ISTR it's not functional unless "sync playback to display" is enabled .. and for general best results with Kodi on a normal TV you want to leave that setting disabled.
Your personal "most important feature" is probably used by 0.00001% of Kodi users, and that's why it's not the default or on some kind of hot-button. Fortunately Kodi is an extensible and scriptable platform so you should be able to (with a little fiddling) toggle the sync-playback-to-display feature via a JSON API request which can be put into a shell script which is mapped to a spare remote button through a custom keymap. There's no HOWTO guide for doing exactly that I can point you to, but all the individual bits for doing that workflow are out there in wiki's and such.
Maybe a course of amphetimines would do the trick. Save on all the coding stuff too 😂
The idea of watching videos at the wrong speed is abhorrent to me, but one mans chalk is another mans cheese. If the old release works better, use it. There's no rule that says "thou must upgrade" all the time. There are still ~40% of our active RPi installs on LE 9.2.8. Kodi stats are less accurate than ours (we have some basic stats, they only estimate) but the current percentage estimate means my guess above is missing a bunch of zero's.
I'm now seeing the latest version doesn't even have analogue output as an audio option anymore. So that's a definite deal-breaker for me with my old stereo system. Apparently I'm expected to either replace my hardware/stereo, or buy an additional adapter (micro-HDMI to audio) just because Kodi thinks I should be limited to just HDMI and bluetooth outputs?
Add "dtparam=audio=on" to config.txt.
if only "0.00001% of Kodi users" want faster speed, then even if I'm the ONLY one
You´´ re not alone punto 
It´ s really strange that this feature won´ t get more weight in the Kodi/L_Elec "world" ....VLC or MX Player making this with good results,even big worms like Youtube had implented this feature.
Estuary Skin,Keymap Editor....wonderful 
Works fine on RaspB5 with latest nightly build.
