I've also used Karabiner for remapping some buttons/features on a Razer Orbweaver gaming keyboard (since Razer doesn't support running the config software on macOS), and it seems to work really well.
I believe I was originally hoping/looking to do it with BetterTouchTool, but for whatever reason I found myself going a different way and using Karabiner.. I wonder if that was because I couldn't easily create shortcuts that would only run on that device (not override my normal keyboard)?
I know under 'Trigger Conditions' we can choose 'Works on keyboards with same type as used for recording':
But in my testing, that doesn't seem to restrict it in the way I would have expected.
Eg. I just used my Razer Orbweaver to record a keyboard shortcut for 1, and then typed 1 on my Apple Magic Keyboard, which triggered the shortcut.
With Karabiner I can create 'key remappings' and know they will work well.