I can reproduce that, used any-old-leica firewire TWAIN installer and can find the file cxImagicU.dll and get that error in Gimp.
Very much a longshot, copy that file cxImagicU.dll from your installation to the Gimp directory C:\Program Files\GIMP 2\bin and at least the device now shows up in Gimp.
Obviously, not having a leica to attach, that is as far as I can go. No guarantees that there is no further error waiting to show up
Very much a longshot, copy that file cxImagicU.dll from your installation to the Gimp directory C:\Program Files\GIMP 2\bin and at least the device now shows up in Gimp.
Obviously, not having a leica to attach, that is as far as I can go. No guarantees that there is no further error waiting to show up