Hi @coffeethought, I’ve tried keymap=se with mir-kiosk and that works for me 
. (The end of the top “qwerty” row has the expected accented characters, for example.)
Obviously, I’m doing something a little differently than you but that is probably down to the awkwardness around configuring mir-kiosk.
Rather than trying to figure out what we are doing differently I would strongly recommend using Ubuntu Frame in place of mir-kiosk as does all the same things and more and it is much easier to configure.
The corresponding configuration notes for Frame are here:
https://github.com/MirServer/ubuntu-frame/blob/master/REFERENCE.md
All the same options (and specifically, keymap=se) work, but are easier to get right.
HTH