I completely forgot that LibreELEC 8 still used the old, proprietary amremote / remote.conf mechanism on Amlogic devices. In LE 9 this was switched to ir-keytable so the same mechanism like on all other Linux devices can be used. This is probably the reason why you got keyboard events on LE8 and the keycodes are a bit different.
As for the non-working buttons: quite probably the keytable contains problematic KEY_ values that Kodi can't handle.
To find out which ones they are stop kodi and eventlircd and run "ir-keytable -t", then look at the KEY_xxx values of the non-working buttons.
Then copy the wetek_play_2 keytable from /usr/lib/udev/rc_keymaps to .config/rc_keymaps and change the problematic KEY_xxx entries to something kodi can handle - KEY_F1..KEY_F15 should work for example (any other keys that you'd typically find on a normal keyboard should work fine, too).
Then activate and test the keytable as described on the wiki page.
I had a quick look at the wetek_play_2 keytable and found a few odd entries like KEY_COMPOSE or KEY_CAPSLOCK. These could be problematic.
so long,
Hias