Connecting a mouse disturbs keyboard configuration

Hello,

I am not sure this is the right forum, but this is a very Mac centered question, so I guess it's better than any other sub-forum.

I recently acquired a Nightsword mouse, which I intend to use with my computer running MacOS X.13 (aka High Sierra). On the first connection of the mouse to the computer, it fired up the Keyboard Setup Assistant, the application that allows MacOS to determine which kind of keybaord layout you have. It's either ANSI (US keyboards), ISO (European keyboards) or JIP (Japanese).

I have a european keyboard, a totally passive one (Logitech K310 Washable) which requires no specific setup application. But now, the computer thinks it's an ANSI keyboard. Essentially, one key is missing in the keyboard visualizer (whatever its true name), and two keys have exchanged their role with respect to what

The thing is, MacOS recognizes the Nightsword mouse as both a mouse and a keyboard… This prevents me from forcing the layout, at least through the usual interface! This issue is rather deep, because after some search, I found that the layout type is stored in the file /Library/Preferences/com.apple.keyboardtype.plist, but even using a file from my disk save does not restore the layout!

So the question is: has someone here experienced the same issue? Is there any solution? Maybe there is some (not-so-)hidden option somewhere that I have overlooked?

Thanks in advance!