So I didn't order the remote for my Shield TV and I just connected my Ortek VRC-1100 USB remote from my old HTPC to the Shield and it surprisingly worked almost perfectly.
But some buttons don't work or have the wrong mapping, so I was looking for an app which can remap those buttons, do you know any?
You can remap the keys yourself per usb device however I believe this requires root. I've done this with a USB remote on my nexus player.
See this link to get you started in that direction https://source.android.com/devices/input/key-layout-files.html
this app requires no root and works great for several controllers i use with my nnexus player https://play.google.com/store/apps/details?id=com.apedroid.hwkeyboardhelper
In general ATV is lacking a lot of user-customization... I haven't heard of any RS232 interfaces, the Android TV Remote app/protocol is closed, you're bound to have the leanback keyboard layout of the language you select on your box.
I'd not have much hope that there's anything that can help you with remapping a USB HID as it is in this case.
Edit: my doubts put to shame... please report back if you get tincore and/or another solution to work, and whether or not root is required.
Edit 2: Yes! just down-vote me for stating the obvious; Google wants ONE user experience, which is NOT compatible with customization, which also excludes ATV from hotel rooms or other hospitality services, which are actually VERY good places to do marketing... Have you ever wanted a Demo or a Trailer before you bought a game or a movie?
/r/AndroidTV ... you're hurting yourself in trying to hide/choke whatever trouble actually exists with ATV...
Tincore or multi language key mapper may solve your problem