This is the only picture I have. I fully agree it is an obscure type!
Number built including prototype was 24 only.
The type never had an Allied code name as its existence was unknown until spring 1945.
Details can be found in:
William Green, Flying boats, Vol 5 of War planes of the second World War, Macdonald 1962.
It is one of the famous 'little square book' series from the sixties!!