No. It's a limitation everyone runs into who's not using the en-US keyboard scheme.
Basically, what you need to do is this:
Install an en-US keyboard layout - in Windows 10 you can quickly switch between the two of them like this:
Can't speak for other OS but it should be similar.
Then go into the layout editor. Switch to the en-US layout and type in the key upon which your "non-standard" Swedish key resides.
For instance, in Germany the letters y and z are switched, compared to en-US. Thus in order to get a "y" when I use the Twiddler with a German layout, I need to specify a "z" in the layout editor. Like this:
You can see by the chording codes that y and z traded slots. You will have to do that for every character on your keyboard which is different from the standard QWERTZ layout.
Basically, it's an oversight of tekgear which they will hopefully remedy in the next version because frankly, it's a massive pain in the butt when you're trying to reconfigure layouts - you simply lose track which letter went where because all you're seeing are the en-US characters.
The problem is not easily solved if they insist on keeping the Javascript version of the tuner - because that one does not have direct access to the USB / Bluetooth protocols and thus can't access the actual key codes behind the characters. If I had the time I'd have written a more useful version of the tuner long ago.