Hi mapping team!
Comments on the difference between Karabiner and Ukulele. Both seem well supported.
Karabiner installs software fairly deep into the operating system to redirect keystrokes as defined by the mapping fed to the background resident karabiner programs.
Ukulele defines a new keyboard definition file as if you'd built a new hardware keyboard with a different layout that you wanted to install on the mac. It installs the new keyboard definition with the others (eg British, QUERTZ etc) already on the system. As such it is a lighter approach. As the keyboard definition files are standard this works well with Sonoma (well it has with me anyway).
Ukulele can move around the modifier keys so that control presses command instead (etc etc) as well as moving keys around. I only wanted to swap the " and @ keys which it has done admirably.
The karabiner security discussion was interesting and reminded me (I've worked in security for a while) how little I understand about security. I think the attacker would have to know a lot about your machine before taking advantage of any weakness that might exist.
I've not tried the 'maestro' program.
Hope this brings some light to the query. Thanks for raising it!