OK,

I had left the "-print" argument in my script, so setxkbmap wasn't actually doing anything. Now I get the same error ("Error loading new keyboard description") as everyone else (other than qobi).

Does anybody know the point of the blank "-I" (as in "eye") argument? Does it rely on any assumptions about the present working directory from which the command is executed?

Variations on the setxkbmap command get me variations on the error...but nothing that makes me happy.