Yeah Apple doesn't seem to even try to cater to non-US users with their shortcuts. That's the first I've heard of a system-wide back shortcut. You can't type that in my layout. The default switch between windows of a single app shortcut is also impossible, IIRC. One that I always have to reconfigure when I switch editors is the line comment shortcut which defaults usually to something like cmd-/.

I wonder if it's any better on iOS or are you just completely out of luck there when you can't reconfigure the shortcuts?