Sucks that it was done this way.
I just got a sculpt keyboard and mouse (ergonomic) to replace my 5000 series.
I love back and forward buttons on the mouse for browsing and they are also useful in other application scenarios.
It should have been another mouse button which would have been configured to send a keyboard command if desired.
Because its not it can't be re-mapped without effecting the right Windows key.
Its funny that you can change this easily on linux but not Windows without altering how the keyboard input works...
I am not sure why it was logical for a mouse device to send keyboard events and I found out they both are just generic human input devices.
This means their class is neither mouse or keyboard and the usb receiver essentially translates the events it receives and dispatched interrupts for keyboard or mouse events on a virtual device.
This further supports that the button could be remapped however its just not allowed in the software that Microsoft has available and im honestly not sure why.
I dont like needing auto hot keys and while I don't have a general solution for everyone it should be known the driver for the mouse can be modified to send a different event and then you wouldn't need auto hot keys.
You would then only need to select a different mouse model under the Microsoft software and then remap whatever mouse key you had the driver dispatch for the signal which is received from the mouse when that button is physically pressed (which is different from what is received by the usb receiver for the right Windows key).
I used the 5000 profile and the same event it supplied for the forward button and it works fine.
Hope that made sense!