for the longest i've been using 5schatten 's Reborn Remix for my Rpi3B and 3B+ over the composite out (w/ the annoying issue of overscan adjustments resetting but i think thats something with Kodi rather his end, it stoped once but reared after an update)
i've had my Rpi4 for a few days now, and giving up on getting Kodi to run under Raspbian Buster(extremely slow and unresponsive, alot of things graphically break, which i hope get addressed in teh coming months as i hope im not going to be regret being an early adopter for once) searched to see if there was an LibreElec test build up allready. to my surprise you amazing devs allready got a alpha out.
now w/ so early an build, i'd half expect it given it looks to work "Somewhat better" for those over HDMI, i didnt think enabling the composite out would be any harm. (i use my 3B/3B+ in a "Retro Room the 3B+ as a media center and emulation box, and 3B purely as an "Mini Amiga" emulator) over to a 22' CRT TV (hence the use of the output) + im waiting for my Micro HDMI Cable to arrive from amazon on monday (Thanks amazon for messing up a Prime order and delaying it by 4 days >_>)
but after the initial boot and partition resize and Reboot, after it displays the splash screen, a few moments later the activity flashes rapidly (and seems no further activity) and a loud screeching high pitch tone is being played over the audio lines, this i can only assume is an crash.