Regarding multiple key presses, did you try disabling lirc (seem to remember that was a solution in a thread with similar issue)? Can't say I have much experience with remotes. My lirc and eventlircd package is now in sync with LE 9.2, not sure I can be of further help regarding that.
I figured this out.
Your build is missing some standard LE udev rules for some reason. I note the specific issue below but you may wish to review why others are also missing.
In my case "/usr/lib/udev/rules.d/70-input-repeat.rules" fixes this issue.
ACTION=="add", SUBSYSTEM=="input", KERNEL=="event[0-9]*", GOTO="start"
GOTO="end"
LABEL="start"
# don't change eventlircd device settings
ATTRS{name}=="eventlircd", GOTO="end"
# don't change settings of rc remotes
SUBSYSTEMS=="rc", GOTO="end"
# set default repeat delay to 500ms like rc remotes
RUN+="/usr/bin/ir-keytable --delay=500 --device=$devnode"
# make lircd-uinput use same repeat period like keyboards in kodi
ATTRS{name}=="lircd-uinput", \
RUN+="/usr/bin/ir-keytable --period=80 --device=$devnode"
LABEL="end"
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To verify the fix, I copied the file from Vanilla LE to your build in "/storage/.config/udev.rules.d/70-input-repeat.rules"
This will work as a temp resolution for me until it gets included properly in "/usr/lib/udev/rules.d/"
Here are all the rules found in Vanilla LE but not in your build:
70-infrared.rules
70-input-repeat.rules
90-libinput-model-quirks.rules
96-e2scrub.rules
98-eventlircd.rules