Thanks for the comment that I can undo the setting by setting the thing back to 0. Unfortunately, with the suggested setting, the two buttons are not doing anything. I have only tried OneNote and Kindle.
Though, getting boot.img seems to be a bit demanding, per
this post.
RE: being happy - I'm glad to learn a lot about adb, especially getting to know the correct spelling
And, I don't end using the magnetic cover too much anyways. I think the OP of this thread can take over from where we are now, well, if there is a burning need to remap the two keys on the magnetic cover.
Practically, for flipping pages, I use a Bluetooth clicker. (Logitech Spotlight feels good, but only have two functional buttons. And, Boox sells a black page-turner as well.)