i Switched to CoreElec 9.0.0 too. You have to copy the remote.conf file to /.config and restart. After that the Device boot second time and the amremote is activated und the button press fluid again like Krypton.
But you create the remote.conf File for you self. I have the remote.conf File for the Odroid C2 IR for users that need this for this Device.
Here i Found 2 remote.conf Files for WetekPlay but i don't know if it work. First try the remote.conf file if it not work i doubt the remote 2.conf that you must rename to remote.conf wouldn't work too. Good Luck