Hello, thanks for the extensive reply (and as I thought another case of "don't believe wikipedia").
My source for the WNr 45463 is a post on a German forum:
http://www.forum-marinearchiv.de/smf...?topic=19651.0
I now see that the man who posted it is the one who put German seaplane loss lists in the Internet, and repeats this loss in his 1944 list, but without any WNr:
http://luftwaffe-zur-see.de/Seeluft/...n/Jahr1944.htm
(I should have checked this website...)
In this list, the unit is listed as LZGr. (See). I would be interested by the meaning of this unit name. Four of the five losses listed for this unit in 1944 are Cant Z506, all in Germany in March and April 1944. By the way, two are listed at Friedrichshafen on 18 March 1944 for "unknown reason", the USAAF bomber aviation targets there this day.