I'm dvorak layout user on GNOME. And I'm using SCIM to type East Asian languages.
In default setting, SCIM doesn't works rightly on dvorak layout.
To use SCIM on dvorak layout, I should open 'SCIM Input Method Setup' window, and change Keybroad layout setting to Dvorak. So it works on GNOME programme, but it still doesn't work on KDE programme.
I'm just tested with Korean language. So I'm not sure other keyboard layout on SCIM also has this problem.
I also tested with KDE in Kubuntu. It has same problem. I cannot type rightly in Kubuntu with Dvorak layout keyboard.