Thanks for the detailed test info!
The patch you linked never made it upstream and as it was constantly breaking with kernel updates we had to drop it.
The "topseed" HID driver seems to be rather similar to the old one (using the same 0xffbc vendor page and almost identical keycodes) so you could try binding this driver to your IR receiver. mceusb is a completely different thing and won't work at all.
An alternative would be to use the zotac driver in lirc, see this older thread for more info [xbmcbuntu] [SOLVED] some buttons not working PHILIPS MCE USB IR Receiver-Spinel plus
The lirc zotac driver is already shipped with LibreELEC so you can skip all the compilation stuff in that thread. But there are a couple of things to be aware of:
You may need to add "usbhid.quirks=0x0471:0x20CC:0x10" to the end of kernel command line (in /flash/syslinux.cfg or /flash/extlinux.conf on X86) to get the /dev/usb/hiddevX device).
As mentioned in the thread the udev rule has to be modified for newer kernels, in LibreELEC creating a /storage/.config/udev.rules.d/99-zotac.rules file with the following content should work (this will give you a /dev/remote symlink as the hiddevX number may change)
SUBSYSTEM=="usbmisc" , ACTION=="add", ATTRS{idVendor}=="0471", ATTRS{idProduct}=="20cc", SYMLINK+="remote"
Then, to use the zotac lirc driver you have top copy /etc/lirc/lirc_options.conf to /storage/.config/lirc_options.conf, edid it and change driver from "default" to "zotac" and device from "/dev/lirc0" to "/dev/remote"
Finally copy the lircd.conf file from that thread to /storage/.config/lircd.conf and reboot.
If you get double buttonpresses from the previous working buttons just comment out these button/keycode lines in the lircd.conf file and only leave those with 0xFFBC... codes in there.
so long,
Hias